build-webkit is writing ENABLE_3D_RENDERING=0 to the feature-defines-overrides.txt file, which is causing 3D CSS transforms to be disabled for builds that are built via build-webkit.
Created attachment 189401 [details] Patch
Comment on attachment 189401 [details] Patch r=me
Comment on attachment 189401 [details] Patch Clearing flags on attachment: 189401 Committed r143532: <http://trac.webkit.org/changeset/143532>
All reviewed patches have been landed. Closing bug.