Fix local reference leaks in debugger and use a cache.

Changed alloc record stack trace element to use jmethodID instead of
JNI weak global references. Added code to delete the local ref
created in AllocRecord::SetType.

Bug: 15886342
External bug: https://code.google.com/p/android/issues/detail?id=72330

Change-Id: Id18e765820baad02246768dc9d633aada60f4fed
2 files changed