[Mac] Temporarily stop clearing zombie objects.

Zombie objects are cleared to '!' to force faster failure.  The bug
involves a containing object being zombied, and then trying to message
something it owns.  This change will provide info on the object being
messaged, and perhaps info on who deallocated it.

BUG=154483


Review URL: https://chromiumcodereview.appspot.com/11359117

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@167021 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed