Revert "Revert "Use IsMarked instead of Mark for profiling info.""

Bug in the original change was that we were infitely looping on the
same inline cache entry, expecting null when it was actually an old
pointer to a GC'ed class object.

bug: 37693252
Test: test.py --jit

This reverts commit 3afefba4.

(cherry picked from commit 13056a17)

Change-Id: Ia637d4a7db4394964d1de5c92370921c98a103fa