Remove setShouldDoFullPaintInvalidationIfSelfPaintingLayer

For now we set the flag on children when overflowClip of a RenderBox
changes. However, even if the layer is self painting, it's not always
necessary to do a full paint invalidation.

Call setMayNeedPaintInvalidation() instead to ensure the children will
be reached during invalidateTreeIfNeeded(). Then invalidation will be
issued if needed according to the change of paintInvalidationRect and
positionFromPaintInvalidationBacking.

If a child is composited, cc will handle any visual updates caused
by the change of overflow clipping, so invalidation of the composited
children is unnecessary.

TEST=existing fast/repaint*overflow*.html
TEST=compositing/repaint/should-not-repaint-composited-descendants-on-overflow-change.html

Review URL: https://codereview.chromium.org/618123006

git-svn-id: svn://svn.chromium.org/blink/trunk@183167 bbb929c8-8fbe-4397-9dbb-9b2b20218538