Consider subpixel accumulation when invalidating paint

Pass repaint rect as LayoutRect to
- RenderObject::invalidatePaintUsingContainer(),
- RenderLayerRepainter::setBackingNeedsRepaintInRect()
- CompositedLayerMapping::setContentsNeedDisplayInRect()
and add subpixel accumulation before passing to GraphicsLayer.

BUG=390605
TEST=fast/sub-pixel/repaint-subpixel-layer-in-subpixel-composited-layer.html
R=leviw@chromium.org

Review URL: https://codereview.chromium.org/353403006

git-svn-id: svn://svn.chromium.org/blink/trunk@177408 bbb929c8-8fbe-4397-9dbb-9b2b20218538