Partially annotate V8 for MemorySanitizer.

This is a part of https://codereview.chromium.org/26006004/.
These changes are enough to run most apps that embed V8 (by additionally
ignoring all memory accesses from V8), but don't help testing V8 itself in any
way.

R=danno@chromium.org

Review URL: https://codereview.chromium.org/27471003

Patch from Evgeniy Stepanov <eugenis@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17331 ce2b1a6d-e550-0410-aec6-3dcde31c8c00