Merged r16355 into 3.20 branch.

Filler sizes have to be Smis, fix x64 breakage.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/25011002

git-svn-id: https://v8.googlecode.com/svn/branches/3.20@16980 ce2b1a6d-e550-0410-aec6-3dcde31c8c00