Drawing accumulated textures (in Accumulatedtextures) is independent
of drawing with render list which causes problems with rendering
order when render list and accumulated textures are flushed. To
solve this we need to combine both so we can check for overlapped
drawing.

Previously drawRect was using RenderList batch drawing but not
drawAlphaRect which is essentially the same as drawRect but
additionally supports alpha value. This adds support to draw
alpha rectangles to RenderList and converts drawAlphaRect.

Change-Id: I82bf0b410e5ebabb13bab7b29a2e53a6fdaa404f