Rollback of r15267, r15263, r15193 in trunk branch in preparation for 3.19 branch

HBoundsCheck shouldn't ignore Tagged input representations unconditionally

Short-circuit embedded cons strings.

Turn on parallel recompilation.

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

Review URL: https://codereview.chromium.org/17585003

git-svn-id: https://v8.googlecode.com/svn/trunk@15283 ce2b1a6d-e550-0410-aec6-3dcde31c8c00