Revert "Revert 100453 - Revert "Revert 100384 - Fix bug in SimulateAttrib0.""

The bug was a unsigned->signed conversion issue. Clang truncates, gcc/vc overflow

TEST=unit tests
BUG=95625
TBR=apatrick@chromium.org

Review URL: http://codereview.chromium.org/7863007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@100494 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed