Version 3.26.31.3 (merged r21299)

Skip write barriers when updating the weak hash table.

BUG=359401,378206
LOG=N
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/329063002

git-svn-id: https://v8.googlecode.com/svn/branches/3.26@21757 ce2b1a6d-e550-0410-aec6-3dcde31c8c00