Revert 100494 - Revert &quotRevert 100453 - Revert &quotRevert 100384 - Fix bug in SimulateAttrib0.&quot&quot

      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

TBR=gman@chromium.org
Review URL: http://codereview.chromium.org/7796015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@100498 0039d316-1c4b-4281-b951-d872f2087c98