Merged r16893, r16906 into trunk branch.

Removed IsDeadCheck.

Build fix for 16877.

R=dslomov@chromium.org
BUG=

Review URL: https://codereview.chromium.org/23935012

git-svn-id: https://v8.googlecode.com/svn/trunk@16907 ce2b1a6d-e550-0410-aec6-3dcde31c8c00