Version 3.28.1.1 (merged r21971)

Revert assertion change from r21933 in Isolate::RunMicrotasks().

TBR=yangguo@chromium.org
BUG=

Review URL: https://codereview.chromium.org/351903002

git-svn-id: https://v8.googlecode.com/svn/trunk@21973 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/trunk' into trunk