Merged r15193, r15263, r15267 into trunk branch.

Turn on parallel recompilation.

Short-circuit embedded cons strings.

HBoundsCheck shouldn't ignore Tagged input representations unconditionally.

BUG=v8:2740
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/17176021

git-svn-id: https://v8.googlecode.com/svn/trunk@15270 ce2b1a6d-e550-0410-aec6-3dcde31c8c00