Bug 1086937 - Patch 0: Add missing null check of root element so this patch series doesn't expose a crash in layout/style/crashtests/472237-1.html. r=birtles, a=lmandel
Bug 1092842 - When setting cliprects on background color display items, don't shrink them to exclude opaque borders (unless there's nonzero border-radius). r=mattwoodrow, a=lmandel

By not excluding opaque borders from the display item cliprects, we produce
a larger opaque area for opaque background items.
Bug 1097437 - Work around Quartz bug where corners of stroked rects don't get a solid color when they should. r=jrmuizel, a=lmandel