Merge r10187, r10188 from the bleeding_edge to the 3.7 branch.

Rescan cells at the end of mark-sweep.  This means they don't need a
write barrier.
Review URL: http://codereview.chromium.org/8816021
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Remove write barriers for cells on x64, ARM and MIPS.
Review URL: http://codereview.chromium.org/8834005
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Review URL: http://codereview.chromium.org/9190007

git-svn-id: http://v8.googlecode.com/svn/branches/3.7@10392 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
11 files changed