Version 3.28.1.2 (merged r21975)

Initialize the Isolate's use_counter_callback_ member

TBR=marja@chromium.org
BUG=

Review URL: https://codereview.chromium.org/346383003

git-svn-id: https://v8.googlecode.com/svn/trunk@21978 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/trunk' into trunk