e.g. http://build.webkit.org/results/Apple%20Win%207%20Release%20(Tests)/r146565%20(33963)/results.html --- /home/buildbot/slave/win-release-tests/build/layout-test-results/compositing/overflow/composited-scrolling-paint-phases-expected.txt 2013-03-21 23:29:16.572860600 -0700 +++ /home/buildbot/slave/win-release-tests/build/layout-test-results/compositing/overflow/composited-scrolling-paint-phases-actual.txt 2013-03-21 23:29:16.571860500 -0700 @@ -45,6 +45,7 @@ (GraphicsLayer (position 0.00 10.00) (bounds 80.00 10.00) + (contentsOpaque 1) (paintingPhases GraphicsLayerPaintBackground GraphicsLayerPaintForeground