Add Unsafe.allocateInstance.

At the moment, mockers are writing dalvik-specific code that pokes
around with our internals and breaks when we change stuff. They're
also supporting Unsafe so they can run on the RI. Everyone's better
off if we just implement the missing Unsafe call.

Bug: 8297640
Change-Id: Ib647e27d920be548009f26ced3b74bad7400a590
5 files changed