Add a way to determine if a large object is a zygote object

Also fix a slight memory leak in LargeObjectMapSpace.

Bug: 20674158

(cherry picked from commit 8f23620d45399286564986d2541cda761b3fe0ac)

Change-Id: I2416df484e5b84a8c5cc0b5664c8cb102dc235f6
5 files changed