diff --git a/V8_MERGE_REVISION b/V8_MERGE_REVISION
index 3c9aae8..9bdc5bd 100644
--- a/V8_MERGE_REVISION
+++ b/V8_MERGE_REVISION
@@ -1,2 +1,2 @@
-V8 3.9.24.13
-http://v8.googlecode.com/svn/branches/3.9@11337
+V8 3.9.24.15
+http://v8.googlecode.com/svn/branches/3.9@11368
diff --git a/src/arm/stub-cache-arm.cc b/src/arm/stub-cache-arm.cc
index 06f8385..852824f 100644
--- a/src/arm/stub-cache-arm.cc
+++ b/src/arm/stub-cache-arm.cc
@@ -443,8 +443,10 @@
   Label exit;
 
   // Check that the map of the object hasn't changed.
+  CompareMapMode mode = transition.is_null() ? ALLOW_ELEMENT_TRANSITION_MAPS
+                                             : REQUIRE_EXACT_MAP;
   __ CheckMap(receiver_reg, scratch, Handle<Map>(object->map()), miss_label,
-              DO_SMI_CHECK, ALLOW_ELEMENT_TRANSITION_MAPS);
+              DO_SMI_CHECK, mode);
 
   // Perform global security token check if needed.
   if (object->IsJSGlobalProxy()) {
diff --git a/src/compiler.cc b/src/compiler.cc
index 2272337..c9c2480 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -531,6 +531,10 @@
     if (extension == NULL && !result.is_null()) {
       compilation_cache->PutScript(source, result);
     }
+  } else {
+    if (result->ic_age() != HEAP->global_ic_age()) {
+      result->ResetForNewContext(HEAP->global_ic_age());
+    }
   }
 
   if (result.is_null()) isolate->ReportPendingMessages();
@@ -586,6 +590,10 @@
       compilation_cache->PutEval(
           source, context, is_global, result, scope_position);
     }
+  } else {
+    if (result->ic_age() != HEAP->global_ic_age()) {
+      result->ResetForNewContext(HEAP->global_ic_age());
+    }
   }
 
   return result;
diff --git a/src/factory.cc b/src/factory.cc
index 143099c..e8a9f26 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -537,6 +537,10 @@
           : isolate()->strict_mode_function_map(),
       pretenure);
 
+  if (function_info->ic_age() != isolate()->heap()->global_ic_age()) {
+    function_info->ResetForNewContext(isolate()->heap()->global_ic_age());
+  }
+
   result->set_context(*context);
   if (!function_info->bound()) {
     int number_of_literals = function_info->num_literals();
diff --git a/src/full-codegen.cc b/src/full-codegen.cc
index d963979..531eed2 100644
--- a/src/full-codegen.cc
+++ b/src/full-codegen.cc
@@ -327,6 +327,7 @@
   code->set_compiled_optimizable(info->IsOptimizable());
 #endif  // ENABLE_DEBUGGER_SUPPORT
   code->set_allow_osr_at_loop_nesting_level(0);
+  code->set_profiler_ticks(0);
   code->set_stack_check_table_offset(table_offset);
   CodeGenerator::PrintCode(code, info);
   info->SetCode(code);  // May be an empty handle.
diff --git a/src/heap.cc b/src/heap.cc
index a1cccf6..48e8b56 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -145,7 +145,6 @@
       number_idle_notifications_(0),
       last_idle_notification_gc_count_(0),
       last_idle_notification_gc_count_init_(false),
-      idle_notification_will_schedule_next_gc_(false),
       mark_sweeps_since_idle_round_started_(0),
       ms_count_at_last_idle_notification_(0),
       gc_count_at_last_idle_gc_(0),
@@ -504,11 +503,17 @@
       !incremental_marking()->IsStopped() &&
       !incremental_marking()->should_hurry() &&
       FLAG_incremental_marking_steps) {
-    if (FLAG_trace_incremental_marking) {
-      PrintF("[IncrementalMarking] Delaying MarkSweep.\n");
+    // Make progress in incremental marking.
+    const intptr_t kStepSizeWhenDelayedByScavenge = 1 * MB;
+    incremental_marking()->Step(kStepSizeWhenDelayedByScavenge,
+                                IncrementalMarking::NO_GC_VIA_STACK_GUARD);
+    if (!incremental_marking()->IsComplete()) {
+      if (FLAG_trace_incremental_marking) {
+        PrintF("[IncrementalMarking] Delaying MarkSweep.\n");
+      }
+      collector = SCAVENGER;
+      collector_reason = "incremental marking delaying mark-sweep";
     }
-    collector = SCAVENGER;
-    collector_reason = "incremental marking delaying mark-sweep";
   }
 
   bool next_gc_likely_to_collect_more = false;
@@ -1953,7 +1958,7 @@
     if (!maybe_info->To(&info)) return maybe_info;
   }
   info->set_ic_total_count(0);
-  info->set_ic_with_typeinfo_count(0);
+  info->set_ic_with_type_info_count(0);
   info->set_type_feedback_cells(TypeFeedbackCells::cast(empty_fixed_array()),
                                 SKIP_WRITE_BARRIER);
   return info;
@@ -2897,9 +2902,9 @@
   share->set_inferred_name(empty_string(), SKIP_WRITE_BARRIER);
   share->set_initial_map(undefined_value(), SKIP_WRITE_BARRIER);
   share->set_this_property_assignments(undefined_value(), SKIP_WRITE_BARRIER);
-  share->set_deopt_counter(FLAG_deopt_every_n_times);
-  share->set_profiler_ticks(0);
   share->set_ast_node_count(0);
+  share->set_deopt_counter(FLAG_deopt_every_n_times);
+  share->set_ic_age(0);
 
   // Set integer fields (smi or int, depending on the architecture).
   share->set_length(0);
@@ -4817,10 +4822,8 @@
 
 
 void Heap::AdvanceIdleIncrementalMarking(intptr_t step_size) {
-  // This flag prevents incremental marking from requesting GC via stack guard
-  idle_notification_will_schedule_next_gc_ = true;
-  incremental_marking()->Step(step_size);
-  idle_notification_will_schedule_next_gc_ = false;
+  incremental_marking()->Step(step_size,
+                              IncrementalMarking::NO_GC_VIA_STACK_GUARD);
 
   if (incremental_marking()->IsComplete()) {
     bool uncommit = false;
diff --git a/src/heap.h b/src/heap.h
index 2bd037f..0391e0e 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -1569,10 +1569,6 @@
   // The roots that have an index less than this are always in old space.
   static const int kOldSpaceRoots = 0x20;
 
-  bool idle_notification_will_schedule_next_gc() {
-    return idle_notification_will_schedule_next_gc_;
-  }
-
   uint32_t HashSeed() {
     uint32_t seed = static_cast<uint32_t>(hash_seed()->value());
     ASSERT(FLAG_randomize_hashes || seed == 0);
@@ -2033,7 +2029,6 @@
   unsigned int last_idle_notification_gc_count_;
   bool last_idle_notification_gc_count_init_;
 
-  bool idle_notification_will_schedule_next_gc_;
   int mark_sweeps_since_idle_round_started_;
   int ms_count_at_last_idle_notification_;
   unsigned int gc_count_at_last_idle_gc_;
diff --git a/src/ia32/stub-cache-ia32.cc b/src/ia32/stub-cache-ia32.cc
index fd26779..5a5afdc 100644
--- a/src/ia32/stub-cache-ia32.cc
+++ b/src/ia32/stub-cache-ia32.cc
@@ -746,8 +746,10 @@
                                       Register scratch,
                                       Label* miss_label) {
   // Check that the map of the object hasn't changed.
+  CompareMapMode mode = transition.is_null() ? ALLOW_ELEMENT_TRANSITION_MAPS
+                                             : REQUIRE_EXACT_MAP;
   __ CheckMap(receiver_reg, Handle<Map>(object->map()),
-              miss_label, DO_SMI_CHECK, ALLOW_ELEMENT_TRANSITION_MAPS);
+              miss_label, DO_SMI_CHECK, mode);
 
   // Perform global security token check if needed.
   if (object->IsJSGlobalProxy()) {
diff --git a/src/ic.cc b/src/ic.cc
index c762127..b8d4b40 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -296,58 +296,44 @@
 }
 
 
+static int ComputeTypeInfoCountDelta(IC::State old_state, IC::State new_state) {
+  bool was_uninitialized =
+      old_state == UNINITIALIZED || old_state == PREMONOMORPHIC;
+  bool is_uninitialized =
+      new_state == UNINITIALIZED || new_state == PREMONOMORPHIC;
+  return (was_uninitialized && !is_uninitialized) ?  1 :
+         (!was_uninitialized && is_uninitialized) ? -1 : 0;
+}
+
+
 void IC::PostPatching(Address address, Code* target, Code* old_target) {
-  if (FLAG_type_info_threshold > 0) {
-    if (old_target->is_inline_cache_stub() &&
-        target->is_inline_cache_stub()) {
-      State old_state = old_target->ic_state();
-      State new_state = target->ic_state();
-      bool was_uninitialized =
-          old_state == UNINITIALIZED || old_state == PREMONOMORPHIC;
-      bool is_uninitialized =
-          new_state == UNINITIALIZED || new_state == PREMONOMORPHIC;
-      int delta = 0;
-      if (was_uninitialized && !is_uninitialized) {
-        delta = 1;
-      } else if (!was_uninitialized && is_uninitialized) {
-        delta = -1;
-      }
-      if (delta != 0) {
-        Code* host = target->GetHeap()->isolate()->
-            inner_pointer_to_code_cache()->GetCacheEntry(address)->code;
-        // Not all Code objects have TypeFeedbackInfo.
-        if (host->type_feedback_info()->IsTypeFeedbackInfo()) {
-          TypeFeedbackInfo* info =
-              TypeFeedbackInfo::cast(host->type_feedback_info());
-          info->set_ic_with_typeinfo_count(
-              info->ic_with_typeinfo_count() + delta);
-        }
-      }
+  if (FLAG_type_info_threshold == 0 && !FLAG_watch_ic_patching) {
+    return;
+  }
+  Code* host = target->GetHeap()->isolate()->
+      inner_pointer_to_code_cache()->GetCacheEntry(address)->code;
+  if (host->kind() != Code::FUNCTION) return;
+
+  if (FLAG_type_info_threshold > 0 &&
+      old_target->is_inline_cache_stub() &&
+      target->is_inline_cache_stub()) {
+    int delta = ComputeTypeInfoCountDelta(old_target->ic_state(),
+                                          target->ic_state());
+    // Not all Code objects have TypeFeedbackInfo.
+    if (delta != 0 && host->type_feedback_info()->IsTypeFeedbackInfo()) {
+      TypeFeedbackInfo* info =
+          TypeFeedbackInfo::cast(host->type_feedback_info());
+      info->set_ic_with_type_info_count(
+          info->ic_with_type_info_count() + delta);
     }
   }
   if (FLAG_watch_ic_patching) {
+    host->set_profiler_ticks(0);
     Isolate::Current()->runtime_profiler()->NotifyICChanged();
-    // We do not want to optimize until the ICs have settled down,
-    // so when they are patched, we postpone optimization for the
-    // current function and the functions above it on the stack that
-    // might want to inline this one.
-    StackFrameIterator it;
-    if (it.done()) return;
-    it.Advance();
-    static const int kStackFramesToMark = Compiler::kMaxInliningLevels - 1;
-    for (int i = 0; i < kStackFramesToMark; ++i) {
-      if (it.done()) return;
-      StackFrame* raw_frame = it.frame();
-      if (raw_frame->is_java_script()) {
-        JSFunction* function =
-            JSFunction::cast(JavaScriptFrame::cast(raw_frame)->function());
-        if (function->IsOptimized()) continue;
-        SharedFunctionInfo* shared = function->shared();
-        shared->set_profiler_ticks(0);
-      }
-      it.Advance();
-    }
   }
+  // TODO(2029): When an optimized function is patched, it would
+  // be nice to propagate the corresponding type information to its
+  // unoptimized version for the benefit of later inlining.
 }
 
 
diff --git a/src/incremental-marking.cc b/src/incremental-marking.cc
index 8fe89b4..7bbd521 100644
--- a/src/incremental-marking.cc
+++ b/src/incremental-marking.cc
@@ -205,6 +205,12 @@
     MarkObject(target);
   }
 
+  void VisitSharedFunctionInfo(SharedFunctionInfo* shared) {
+    if (shared->ic_age() != heap_->global_ic_age()) {
+      shared->ResetForNewContext(heap_->global_ic_age());
+    }
+  }
+
   void VisitPointer(Object** p) {
     Object* obj = *p;
     if (obj->NonFailureIsHeapObject()) {
@@ -743,7 +749,7 @@
 }
 
 
-void IncrementalMarking::MarkingComplete() {
+void IncrementalMarking::MarkingComplete(CompletionAction action) {
   state_ = COMPLETE;
   // We will set the stack guard to request a GC now.  This will mean the rest
   // of the GC gets performed as soon as possible (we can't do a GC here in a
@@ -754,13 +760,14 @@
   if (FLAG_trace_incremental_marking) {
     PrintF("[IncrementalMarking] Complete (normal).\n");
   }
-  if (!heap_->idle_notification_will_schedule_next_gc()) {
+  if (action == GC_VIA_STACK_GUARD) {
     heap_->isolate()->stack_guard()->RequestGC();
   }
 }
 
 
-void IncrementalMarking::Step(intptr_t allocated_bytes) {
+void IncrementalMarking::Step(intptr_t allocated_bytes,
+                              CompletionAction action) {
   if (heap_->gc_state() != Heap::NOT_IN_GC ||
       !FLAG_incremental_marking ||
       !FLAG_incremental_marking_steps ||
@@ -833,7 +840,7 @@
       Marking::MarkBlack(obj_mark_bit);
       MemoryChunk::IncrementLiveBytesFromGC(obj->address(), size);
     }
-    if (marking_deque_.IsEmpty()) MarkingComplete();
+    if (marking_deque_.IsEmpty()) MarkingComplete(action);
   }
 
   allocated_ = 0;
diff --git a/src/incremental-marking.h b/src/incremental-marking.h
index 4f8fa6b..8cbe6c1 100644
--- a/src/incremental-marking.h
+++ b/src/incremental-marking.h
@@ -46,6 +46,11 @@
     COMPLETE
   };
 
+  enum CompletionAction {
+    GC_VIA_STACK_GUARD,
+    NO_GC_VIA_STACK_GUARD
+  };
+
   explicit IncrementalMarking(Heap* heap);
 
   void TearDown();
@@ -82,7 +87,7 @@
 
   void Abort();
 
-  void MarkingComplete();
+  void MarkingComplete(CompletionAction action);
 
   // It's hard to know how much work the incremental marker should do to make
   // progress in the face of the mutator creating new work for it.  We start
@@ -102,10 +107,11 @@
   static const intptr_t kMaxAllocationMarkingFactor = 1000;
 
   void OldSpaceStep(intptr_t allocated) {
-    Step(allocated * kFastMarking / kInitialAllocationMarkingFactor);
+    Step(allocated * kFastMarking / kInitialAllocationMarkingFactor,
+         GC_VIA_STACK_GUARD);
   }
 
-  void Step(intptr_t allocated);
+  void Step(intptr_t allocated, CompletionAction action);
 
   inline void RestartIfNotMarking() {
     if (state_ == COMPLETE) {
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index dde172d..b4f488b 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -1406,6 +1406,10 @@
 
     if (shared->IsInobjectSlackTrackingInProgress()) shared->DetachInitialMap();
 
+    if (shared->ic_age() != heap->global_ic_age()) {
+      shared->ResetForNewContext(heap->global_ic_age());
+    }
+
     if (!known_flush_code_candidate) {
       known_flush_code_candidate = IsFlushable(heap, shared);
       if (known_flush_code_candidate) {
diff --git a/src/mips/stub-cache-mips.cc b/src/mips/stub-cache-mips.cc
index 294bc0a..f7b94b9 100644
--- a/src/mips/stub-cache-mips.cc
+++ b/src/mips/stub-cache-mips.cc
@@ -429,8 +429,10 @@
   // a0 : value.
   Label exit;
   // Check that the map of the object hasn't changed.
+  CompareMapMode mode = transition.is_null() ? ALLOW_ELEMENT_TRANSITION_MAPS
+                                             : REQUIRE_EXACT_MAP;
   __ CheckMap(receiver_reg, scratch, Handle<Map>(object->map()), miss_label,
-              DO_SMI_CHECK, ALLOW_ELEMENT_TRANSITION_MAPS);
+              DO_SMI_CHECK, mode);
 
   // Perform global security token check if needed.
   if (object->IsJSGlobalProxy()) {
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 78578cc..6c2c73a 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -3088,6 +3088,19 @@
 }
 
 
+int Code::profiler_ticks() {
+  ASSERT(kind() == FUNCTION);
+  return READ_BYTE_FIELD(this, kProfilerTicksOffset);
+}
+
+
+void Code::set_profiler_ticks(int ticks) {
+  ASSERT(kind() == FUNCTION);
+  ASSERT(ticks < 256);
+  WRITE_BYTE_FIELD(this, kProfilerTicksOffset, ticks);
+}
+
+
 unsigned Code::stack_slots() {
   ASSERT(kind() == OPTIMIZED_FUNCTION);
   return READ_UINT32_FIELD(this, kStackSlotsOffset);
@@ -3507,8 +3520,8 @@
 ACCESSORS(SharedFunctionInfo, inferred_name, String, kInferredNameOffset)
 ACCESSORS(SharedFunctionInfo, this_property_assignments, Object,
           kThisPropertyAssignmentsOffset)
+SMI_ACCESSORS(SharedFunctionInfo, ic_age, kICAgeOffset)
 
-SMI_ACCESSORS(SharedFunctionInfo, profiler_ticks, kProfilerTicksOffset)
 
 BOOL_ACCESSORS(FunctionTemplateInfo, flag, hidden_prototype,
                kHiddenPrototypeBit)
@@ -4814,7 +4827,7 @@
 
 
 SMI_ACCESSORS(TypeFeedbackInfo, ic_total_count, kIcTotalCountOffset)
-SMI_ACCESSORS(TypeFeedbackInfo, ic_with_typeinfo_count,
+SMI_ACCESSORS(TypeFeedbackInfo, ic_with_type_info_count,
               kIcWithTypeinfoCountOffset)
 ACCESSORS(TypeFeedbackInfo, type_feedback_cells, TypeFeedbackCells,
           kTypeFeedbackCellsOffset)
diff --git a/src/objects-printer.cc b/src/objects-printer.cc
index 38e6138..2353a95 100644
--- a/src/objects-printer.cc
+++ b/src/objects-printer.cc
@@ -559,8 +559,8 @@
 
 void TypeFeedbackInfo::TypeFeedbackInfoPrint(FILE* out) {
   HeapObject::PrintHeader(out, "TypeFeedbackInfo");
-  PrintF(out, "\n - ic_total_count: %d, ic_with_typeinfo_count: %d",
-         ic_total_count(), ic_with_typeinfo_count());
+  PrintF(out, "\n - ic_total_count: %d, ic_with_type_info_count: %d",
+         ic_total_count(), ic_with_type_info_count());
   PrintF(out, "\n - type_feedback_cells: ");
   type_feedback_cells()->FixedArrayPrint(out);
 }
diff --git a/src/objects.cc b/src/objects.cc
index 64d85a0..208c75b 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -1390,9 +1390,11 @@
     case EXTERNAL_FLOAT_ARRAY_TYPE:
     case EXTERNAL_DOUBLE_ARRAY_TYPE:
       break;
-    case SHARED_FUNCTION_INFO_TYPE:
-      SharedFunctionInfo::BodyDescriptor::IterateBody(this, v);
+    case SHARED_FUNCTION_INFO_TYPE: {
+      SharedFunctionInfo* shared = reinterpret_cast<SharedFunctionInfo*>(this);
+      shared->SharedFunctionInfoIterateBody(v);
       break;
+    }
 
 #define MAKE_STRUCT_CASE(NAME, Name, name) \
         case NAME##_TYPE:
@@ -7869,6 +7871,22 @@
 }
 
 
+void SharedFunctionInfo::ResetForNewContext(int new_ic_age) {
+  code()->ClearInlineCaches();
+  set_ic_age(new_ic_age);
+  if (code()->kind() == Code::FUNCTION) {
+    code()->set_profiler_ticks(0);
+    if (optimization_disabled() &&
+        opt_count() >= Compiler::kDefaultMaxOptCount) {
+      // Re-enable optimizations if they were disabled due to opt_count limit.
+      set_optimization_disabled(false);
+      code()->set_optimizable(true);
+    }
+    set_opt_count(0);
+  }
+}
+
+
 static void GetMinInobjectSlack(Map* map, void* data) {
   int slack = map->unused_property_fields();
   if (*reinterpret_cast<int*>(data) > slack) {
@@ -7912,6 +7930,12 @@
 }
 
 
+void SharedFunctionInfo::SharedFunctionInfoIterateBody(ObjectVisitor* v) {
+  v->VisitSharedFunctionInfo(this);
+  SharedFunctionInfo::BodyDescriptor::IterateBody(this, v);
+}
+
+
 #define DECLARE_TAG(ignore1, name, ignore2) name,
 const char* const VisitorSynchronization::kTags[
     VisitorSynchronization::kNumberOfSyncTags] = {
@@ -7969,7 +7993,6 @@
   CHECK_EQ(target, old_target);  // VisitPointer doesn't change Code* *target.
 }
 
-
 void ObjectVisitor::VisitEmbeddedPointer(RelocInfo* rinfo) {
   ASSERT(rinfo->rmode() == RelocInfo::EMBEDDED_OBJECT);
   VisitPointer(rinfo->target_object_address());
@@ -8116,6 +8139,21 @@
 }
 
 
+void Code::ClearInlineCaches() {
+  int mask = RelocInfo::ModeMask(RelocInfo::CODE_TARGET) |
+             RelocInfo::ModeMask(RelocInfo::CONSTRUCT_CALL) |
+             RelocInfo::ModeMask(RelocInfo::CODE_TARGET_WITH_ID) |
+             RelocInfo::ModeMask(RelocInfo::CODE_TARGET_CONTEXT);
+  for (RelocIterator it(this, mask); !it.done(); it.next()) {
+    RelocInfo* info = it.rinfo();
+    Code* target(Code::GetCodeFromTargetAddress(info->target_address()));
+    if (target->is_inline_cache_stub()) {
+      IC::Clear(info->pc());
+    }
+  }
+}
+
+
 #ifdef ENABLE_DISASSEMBLER
 
 void DeoptimizationInputData::DeoptimizationInputDataPrint(FILE* out) {
diff --git a/src/objects.h b/src/objects.h
index a9cb8e0..ccd07ff 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4255,6 +4255,11 @@
   inline void set_allow_osr_at_loop_nesting_level(int level);
   inline int allow_osr_at_loop_nesting_level();
 
+  // [profiler_ticks]: For FUNCTION kind, tells for how many profiler ticks
+  // the code object was seen on the stack with no IC patching going on.
+  inline int profiler_ticks();
+  inline void set_profiler_ticks(int ticks);
+
   // [stack_slots]: For kind OPTIMIZED_FUNCTION, the number of stack slots
   // reserved in the code prologue.
   inline unsigned stack_slots();
@@ -4423,6 +4428,7 @@
 #ifdef DEBUG
   void CodeVerify();
 #endif
+  void ClearInlineCaches();
 
   // Max loop nesting marker used to postpose OSR. We don't take loop
   // nesting that is deeper than 5 levels into account.
@@ -4473,6 +4479,7 @@
   static const int kBinaryOpReturnTypeOffset = kBinaryOpTypeOffset + 1;
 
   static const int kAllowOSRAtLoopNestingLevelOffset = kFullCodeFlags + 1;
+  static const int kProfilerTicksOffset = kAllowOSRAtLoopNestingLevelOffset + 1;
 
   static const int kSafepointTableOffsetOffset = kStackSlotsOffset + kIntSize;
   static const int kStackCheckTableOffsetOffset = kStackSlotsOffset + kIntSize;
@@ -5323,16 +5330,18 @@
   inline int compiler_hints();
   inline void set_compiler_hints(int value);
 
+  inline int ast_node_count();
+  inline void set_ast_node_count(int count);
+
   // A counter used to determine when to stress the deoptimizer with a
   // deopt.
   inline int deopt_counter();
   inline void set_deopt_counter(int counter);
 
-  inline int profiler_ticks();
-  inline void set_profiler_ticks(int ticks);
-
-  inline int ast_node_count();
-  inline void set_ast_node_count(int count);
+  // Inline cache age is used to infer whether the function survived a context
+  // disposal or not. In the former case we reset the opt_count.
+  inline int ic_age();
+  inline void set_ic_age(int age);
 
   // Add information on assignments of the form this.x = ...;
   void SetThisPropertyAssignmentsInfo(
@@ -5478,6 +5487,8 @@
   void SharedFunctionInfoVerify();
 #endif
 
+  void ResetForNewContext(int new_ic_age);
+
   // Helpers to compile the shared code.  Returns true on success, false on
   // failure (e.g., stack overflow during compilation).
   static bool EnsureCompiled(Handle<SharedFunctionInfo> shared,
@@ -5485,6 +5496,8 @@
   static bool CompileLazy(Handle<SharedFunctionInfo> shared,
                           ClearExceptionFlag flag);
 
+  void SharedFunctionInfoIterateBody(ObjectVisitor* v);
+
   // Casting.
   static inline SharedFunctionInfo* cast(Object* obj);
 
@@ -5508,12 +5521,13 @@
       kInferredNameOffset + kPointerSize;
   static const int kThisPropertyAssignmentsOffset =
       kInitialMapOffset + kPointerSize;
-  static const int kProfilerTicksOffset =
-      kThisPropertyAssignmentsOffset + kPointerSize;
+  // ic_age is a Smi field. It could be grouped with another Smi field into a
+  // PSEUDO_SMI_ACCESSORS pair (on x64), if one becomes available.
+  static const int kICAgeOffset = kThisPropertyAssignmentsOffset + kPointerSize;
 #if V8_HOST_ARCH_32_BIT
   // Smi fields.
   static const int kLengthOffset =
-      kProfilerTicksOffset + kPointerSize;
+      kICAgeOffset + kPointerSize;
   static const int kFormalParameterCountOffset = kLengthOffset + kPointerSize;
   static const int kExpectedNofPropertiesOffset =
       kFormalParameterCountOffset + kPointerSize;
@@ -5532,8 +5546,9 @@
   static const int kOptCountOffset =
       kThisPropertyAssignmentsCountOffset + kPointerSize;
   static const int kAstNodeCountOffset = kOptCountOffset + kPointerSize;
-  static const int kDeoptCounterOffset =
-      kAstNodeCountOffset + kPointerSize;
+  static const int kDeoptCounterOffset = kAstNodeCountOffset + kPointerSize;
+
+
   // Total size.
   static const int kSize = kDeoptCounterOffset + kPointerSize;
 #else
@@ -5547,7 +5562,7 @@
   // word is not set and thus this word cannot be treated as pointer
   // to HeapObject during old space traversal.
   static const int kLengthOffset =
-      kProfilerTicksOffset + kPointerSize;
+      kICAgeOffset + kPointerSize;
   static const int kFormalParameterCountOffset =
       kLengthOffset + kIntSize;
 
@@ -6562,8 +6577,8 @@
   inline int ic_total_count();
   inline void set_ic_total_count(int count);
 
-  inline int ic_with_typeinfo_count();
-  inline void set_ic_with_typeinfo_count(int count);
+  inline int ic_with_type_info_count();
+  inline void set_ic_with_type_info_count(int count);
 
   DECL_ACCESSORS(type_feedback_cells, TypeFeedbackCells)
 
@@ -8531,6 +8546,8 @@
   // Visit pointer embedded into a code object.
   virtual void VisitEmbeddedPointer(RelocInfo* rinfo);
 
+  virtual void VisitSharedFunctionInfo(SharedFunctionInfo* shared) {}
+
   // Visits a contiguous arrays of external references (references to the C++
   // heap) in the half-open range [start, end). Any or all of the values
   // may be modified on return.
diff --git a/src/runtime-profiler.cc b/src/runtime-profiler.cc
index 6ed4ff4..b06168a 100644
--- a/src/runtime-profiler.cc
+++ b/src/runtime-profiler.cc
@@ -65,6 +65,12 @@
 // Number of times a function has to be seen on the stack before it is
 // optimized.
 static const int kProfilerTicksBeforeOptimization = 2;
+// If a function does not have enough type info (according to
+// FLAG_type_info_threshold), but has seen a huge number of ticks,
+// optimize it as it is.
+static const int kTicksWhenNotEnoughTypeInfo = 100;
+// We only have one byte to store the number of ticks.
+STATIC_ASSERT(kTicksWhenNotEnoughTypeInfo < 256);
 
 // Maximum size in bytes of generated code for a function to be optimized
 // the very first time it is seen on the stack.
@@ -103,20 +109,20 @@
 
 
 static void GetICCounts(JSFunction* function,
-                        int* ic_with_typeinfo_count,
+                        int* ic_with_type_info_count,
                         int* ic_total_count,
                         int* percentage) {
   *ic_total_count = 0;
-  *ic_with_typeinfo_count = 0;
+  *ic_with_type_info_count = 0;
   Object* raw_info =
       function->shared()->code()->type_feedback_info();
   if (raw_info->IsTypeFeedbackInfo()) {
     TypeFeedbackInfo* info = TypeFeedbackInfo::cast(raw_info);
-    *ic_with_typeinfo_count = info->ic_with_typeinfo_count();
+    *ic_with_type_info_count = info->ic_with_type_info_count();
     *ic_total_count = info->ic_total_count();
   }
   *percentage = *ic_total_count > 0
-      ? 100 * *ic_with_typeinfo_count / *ic_total_count
+      ? 100 * *ic_with_type_info_count / *ic_total_count
       : 100;
 }
 
@@ -259,13 +265,14 @@
       }
     }
 
-    if (function->IsMarkedForLazyRecompilation() &&
-        function->shared()->code()->kind() == Code::FUNCTION) {
-      Code* unoptimized = function->shared()->code();
-      int nesting = unoptimized->allow_osr_at_loop_nesting_level();
+    Code* shared_code = function->shared()->code();
+    if (shared_code->kind() != Code::FUNCTION) continue;
+
+    if (function->IsMarkedForLazyRecompilation()) {
+      int nesting = shared_code->allow_osr_at_loop_nesting_level();
       if (nesting == 0) AttemptOnStackReplacement(function);
       int new_nesting = Min(nesting + 1, Code::kMaxLoopNestingMarker);
-      unoptimized->set_allow_osr_at_loop_nesting_level(new_nesting);
+      shared_code->set_allow_osr_at_loop_nesting_level(new_nesting);
     }
 
     // Do not record non-optimizable functions.
@@ -283,7 +290,7 @@
     }
 
     if (FLAG_watch_ic_patching) {
-      int ticks = function->shared()->profiler_ticks();
+      int ticks = shared_code->profiler_ticks();
 
       if (ticks >= kProfilerTicksBeforeOptimization) {
         int typeinfo, total, percentage;
@@ -292,12 +299,10 @@
           // If this particular function hasn't had any ICs patched for enough
           // ticks, optimize it now.
           Optimize(function, "hot and stable");
-        } else if (ticks >= 100) {
-          // If this function does not have enough type info, but has
-          // seen a huge number of ticks, optimize it as it is.
+        } else if (ticks >= kTicksWhenNotEnoughTypeInfo) {
           Optimize(function, "not much type info but very hot");
         } else {
-          function->shared()->set_profiler_ticks(ticks + 1);
+          shared_code->set_profiler_ticks(ticks + 1);
           if (FLAG_trace_opt_verbose) {
             PrintF("[not yet optimizing ");
             function->PrintName();
@@ -306,7 +311,7 @@
           }
         }
       } else if (!any_ic_changed_ &&
-          function->shared()->code()->instruction_size() < kMaxSizeEarlyOpt) {
+          shared_code->instruction_size() < kMaxSizeEarlyOpt) {
         // If no IC was patched since the last tick and this function is very
         // small, optimistically optimize it now.
         Optimize(function, "small function");
@@ -319,7 +324,7 @@
         // then type info might already be stable and we can optimize now.
         Optimize(function, "stable on startup");
       } else {
-        function->shared()->set_profiler_ticks(ticks + 1);
+        shared_code->set_profiler_ticks(ticks + 1);
       }
     } else {  // !FLAG_watch_ic_patching
       samples[sample_count++] = function;
diff --git a/src/runtime.cc b/src/runtime.cc
index 320ab59..82ffdd0 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -8043,8 +8043,6 @@
   ASSERT(args.length() == 1);
   Handle<JSFunction> function = args.at<JSFunction>(0);
 
-  function->shared()->set_profiler_ticks(0);
-
   // If the function is not compiled ignore the lazy
   // recompilation. This can happen if the debugger is activated and
   // the function is returned to the not compiled state.
@@ -8067,6 +8065,7 @@
     function->ReplaceCode(function->shared()->code());
     return function->code();
   }
+  function->shared()->code()->set_profiler_ticks(0);
   if (JSFunction::CompileOptimized(function,
                                    AstNode::kNoNumber,
                                    CLEAR_EXCEPTION)) {
diff --git a/src/spaces.cc b/src/spaces.cc
index defe352..57b223f 100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -1198,13 +1198,15 @@
         allocation_info_.limit + inline_allocation_limit_step_,
         high);
     int bytes_allocated = static_cast<int>(new_top - top_on_previous_step_);
-    heap()->incremental_marking()->Step(bytes_allocated);
+    heap()->incremental_marking()->Step(
+        bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
     top_on_previous_step_ = new_top;
     return AllocateRaw(size_in_bytes);
   } else if (AddFreshPage()) {
     // Switched to new page. Try allocating again.
     int bytes_allocated = static_cast<int>(old_top - top_on_previous_step_);
-    heap()->incremental_marking()->Step(bytes_allocated);
+    heap()->incremental_marking()->Step(
+        bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
     top_on_previous_step_ = to_space_.page_low();
     return AllocateRaw(size_in_bytes);
   } else {
diff --git a/src/version.cc b/src/version.cc
index c4fc0d7..b7fd7cb 100644
--- a/src/version.cc
+++ b/src/version.cc
@@ -35,7 +35,7 @@
 #define MAJOR_VERSION     3
 #define MINOR_VERSION     9
 #define BUILD_NUMBER      24
-#define PATCH_LEVEL       13
+#define PATCH_LEVEL       15
 // Use 1 for candidates and 0 otherwise.
 // (Boolean macro values are not supported by all preprocessors.)
 #define IS_CANDIDATE_VERSION 0
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index f07f6b6..a275f55 100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -730,8 +730,10 @@
                                       Register scratch,
                                       Label* miss_label) {
   // Check that the map of the object hasn't changed.
+  CompareMapMode mode = transition.is_null() ? ALLOW_ELEMENT_TRANSITION_MAPS
+                                             : REQUIRE_EXACT_MAP;
   __ CheckMap(receiver_reg, Handle<Map>(object->map()),
-              miss_label, DO_SMI_CHECK, ALLOW_ELEMENT_TRANSITION_MAPS);
+              miss_label, DO_SMI_CHECK, mode);
 
   // Perform global security token check if needed.
   if (object->IsJSGlobalProxy()) {
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index 999e2c6..f97bf17 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -1521,17 +1521,13 @@
 
   while (!Marking::IsBlack(Marking::MarkBitFrom(f->code())) &&
          !marking->IsStopped()) {
-    marking->Step(MB);
+    // Discard any pending GC requests otherwise we will get GC when we enter
+    // code below.
+    marking->Step(MB, IncrementalMarking::NO_GC_VIA_STACK_GUARD);
   }
 
   CHECK(marking->IsMarking());
 
-  // Discard any pending GC requests otherwise we will get GC when we enter
-  // code below.
-  if (ISOLATE->stack_guard()->IsGCRequest()) {
-    ISOLATE->stack_guard()->Continue(GC_REQUEST);
-  }
-
   {
     v8::HandleScope scope;
     v8::Handle<v8::Object> global = v8::Context::GetCurrent()->Global();
@@ -1597,3 +1593,90 @@
   HEAP->CollectAllGarbage(Heap::kNoGCFlags);
   CHECK(map->GetPrototypeTransition(*prototype)->IsMap());
 }
+
+
+TEST(ResetSharedFunctionInfoCountersDuringIncrementalMarking) {
+  i::FLAG_allow_natives_syntax = true;
+#ifdef DEBUG
+  i::FLAG_verify_heap = true;
+#endif
+  InitializeVM();
+  if (!i::V8::UseCrankshaft()) return;
+  v8::HandleScope outer_scope;
+
+  {
+    v8::HandleScope scope;
+    CompileRun(
+        "function f () {"
+        "  var s = 0;"
+        "  for (var i = 0; i < 100; i++)  s += i;"
+        "  return s;"
+        "}"
+        "f(); f();"
+        "%OptimizeFunctionOnNextCall(f);"
+        "f();");
+  }
+  Handle<JSFunction> f =
+      v8::Utils::OpenHandle(
+          *v8::Handle<v8::Function>::Cast(
+              v8::Context::GetCurrent()->Global()->Get(v8_str("f"))));
+  CHECK(f->IsOptimized());
+
+  IncrementalMarking* marking = HEAP->incremental_marking();
+  marking->Abort();
+  marking->Start();
+
+  // The following two calls will increment HEAP->global_ic_age().
+  const int kLongIdlePauseInMs = 1000;
+  v8::V8::ContextDisposedNotification();
+  v8::V8::IdleNotification(kLongIdlePauseInMs);
+
+  while (!marking->IsStopped() && !marking->IsComplete()) {
+    marking->Step(1 * MB, IncrementalMarking::NO_GC_VIA_STACK_GUARD);
+  }
+
+  CHECK_EQ(HEAP->global_ic_age(), f->shared()->ic_age());
+  CHECK_EQ(0, f->shared()->opt_count());
+  CHECK_EQ(0, f->shared()->code()->profiler_ticks());
+}
+
+
+TEST(ResetSharedFunctionInfoCountersDuringMarkSweep) {
+  i::FLAG_allow_natives_syntax = true;
+#ifdef DEBUG
+  i::FLAG_verify_heap = true;
+#endif
+  InitializeVM();
+  if (!i::V8::UseCrankshaft()) return;
+  v8::HandleScope outer_scope;
+
+  {
+    v8::HandleScope scope;
+    CompileRun(
+        "function f () {"
+        "  var s = 0;"
+        "  for (var i = 0; i < 100; i++)  s += i;"
+        "  return s;"
+        "}"
+        "f(); f();"
+        "%OptimizeFunctionOnNextCall(f);"
+        "f();");
+  }
+  Handle<JSFunction> f =
+      v8::Utils::OpenHandle(
+          *v8::Handle<v8::Function>::Cast(
+              v8::Context::GetCurrent()->Global()->Get(v8_str("f"))));
+  CHECK(f->IsOptimized());
+
+  HEAP->incremental_marking()->Abort();
+
+  // The following two calls will increment HEAP->global_ic_age().
+  // Since incremental marking is off, IdleNotification will do full GC.
+  const int kLongIdlePauseInMs = 1000;
+  v8::V8::ContextDisposedNotification();
+  v8::V8::IdleNotification(kLongIdlePauseInMs);
+
+  CHECK_EQ(HEAP->global_ic_age(), f->shared()->ic_age());
+  CHECK_EQ(0, f->shared()->opt_count());
+  CHECK_EQ(0, f->shared()->code()->profiler_ticks());
+}
diff --git a/test/mjsunit/regress/regress-crbug-122271.js b/test/mjsunit/regress/regress-crbug-122271.js
new file mode 100644
index 0000000..3a99a7f
--- /dev/null
+++ b/test/mjsunit/regress/regress-crbug-122271.js
@@ -0,0 +1,49 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --allow-natives-syntax
+
+// Tests that ElementsKind transitions and regular transitions don't
+// interfere badly with each other.
+
+var a = [0, 0, 0, 1];
+var b = [0, 0, 0, "one"];
+var c = [0, 0, 0, 1];
+c.foo = "baz";
+
+function foo(array) {
+  array.foo = "bar";
+}
+
+assertTrue(%HasFastSmiOnlyElements(a));
+assertTrue(%HasFastElements(b));
+
+foo(a);
+foo(b);
+
+assertTrue(%HasFastSmiOnlyElements(a));
+assertTrue(%HasFastElements(b));