The testcase at LayoutTests/compositing/iframes/iframe-resize.html displays incorrectly on screen when run manually.
RenderLayerCompositor::updateContentLayerOffset() is getting called before widgets have been updated after layout.
This test is disabled too: bug 38888.
Created attachment 60814 [details]
I field bug 41819 to investigate just doing compositing updates after widget updates.
*** Bug 41329 has been marked as a duplicate of this bug. ***