Bug 568392 didn't quite work; DRAWWINDOW_USE_WIDGET_LAYERS is never enabled, on Mac at least. The problem is that browser.xul sets the window width/height to 800x1000, but this is the *outer* width/height. So the actual document height is less than 1000 because we have to subtract the title bar. So not all the <browser> is visible and we never enable the DRAWWINDOW_USE_WIDGET_LAYERS flag.

This patch fixes it by removing the fixed size from the reftest window. We let the window auto-size to the browser element. Of course, on small-screen devices this might not be possible so we still will fall back to not using USE_WIDGET_LAYERS. That's fine. Now, on Mac at least this causes the reftest window inner size to not be exactly 800x1000, it's a couple of pixels bigger. But we just need to check that it's big enough to make the entire <browser> visible. We also need to fix the allocation of canvases so they don't use the window attributes anymore, now that those attributes don't exist. I'm also cleaning up some of the scrolling reftests.

Comment on attachment 455635 [details] [diff] [review] fix r=dbaron, but we probably don't want *two* REFTEST INFO lines here; if you want more info, maybe add it to the one lower in DoDrawWindow

Sure