Bug 976877 - Don't simplify invalidation regions since it leads to poor results. r=roc
Bug 976877 - Don't build optimized layers (color/image) inside inactive layer trees. r=roc
Bug 971720 - Adjust the source pattern transform when masking with RotatedBuffer to take the mask transform into account. r=roc
Bug 971720 - Allow ThebesLayers to be optimized to ColorLayers even if they have rounded rect clipping. r=roc
Bug 971720 - Add tests. r=roc