Enable LayoutState for pages with composited views

When a view isn't composited, renderers that use the view
as their repaint container will actually return null for
containerForRepaint. When the view is composited, however,
every associated renderer will have a repaint container
that corresponds to the owner of the composited layer it
paints into.

LayoutState is used to quickly map renderers that repaint
to the root to the root's coordinate space, but the logic
where it's used hadn't been updated for composited
RenderViews, so it only checked to see if the repaint
container was null, which is never the case when the view
is composited.

This is a performance optimization and should result in no
behavioral changes.

BUG=361754

Review URL: https://codereview.chromium.org/231823002

git-svn-id: svn://svn.chromium.org/blink/trunk@171183 bbb929c8-8fbe-4397-9dbb-9b2b20218538