Adds mm to dimen units

Change-Id: I8a95f2c2ed9fa2af2023866cb949a92d314f51a9
diff --git a/src/main/java/com/xtremelabs/robolectric/res/DimenResourceLoader.java b/src/main/java/com/xtremelabs/robolectric/res/DimenResourceLoader.java
index ec32ad5..5d08ae0 100644
--- a/src/main/java/com/xtremelabs/robolectric/res/DimenResourceLoader.java
+++ b/src/main/java/com/xtremelabs/robolectric/res/DimenResourceLoader.java
@@ -3,8 +3,8 @@
 import org.w3c.dom.Node;
 public class DimenResourceLoader extends XpathResourceXmlLoader implements ResourceValueConverter {
 
-    private static final String[] UNITS = { "dp", "dip", "px", "sp" };
-	
+    private static final String[] UNITS = { "dp", "dip", "px", "sp", "mm" };
+
     private ResourceReferenceResolver<Float> dimenResolver = new ResourceReferenceResolver<Float>("dimen");
 
     public DimenResourceLoader(ResourceExtractor resourceExtractor) {
@@ -33,7 +33,7 @@
     			end = index;
     		}
     	}
-    	
+
         return Float.parseFloat(rawValue.substring(0, end));
     }
 }