Move paint invalidation after compositing update

Now that repaint-after-layout is the new world, we can make
invalidation its own phase. Moving it after compositing update
removes chicken-and-egg bugs that we had in the invalidation code.

The new code invalidates from the layout roots up to the RenderView
so that we can always do a full tree traversal. This shouldn't
trigger extra invalidations and yield to a more simple code.

I checked the new baselines visually and it's overall a neutral
change, where we do better one some tests
(e.g. fast/repaint/intermediate-layout-position-clip.html) and we
do worse on others (e.g. fast/repaint/layout-state-scrolloffset*).
The bulk of the text changes are invalidation going to a different
GraphicsLayer which indicates that we had some compositing
container changes not accounted for.

BUG=360286

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177349

Review URL: https://codereview.chromium.org/351673007

git-svn-id: svn://svn.chromium.org/blink/trunk@177415 bbb929c8-8fbe-4397-9dbb-9b2b20218538