assertRendererClearedPaintInvalidationState is hit

It's possible that we don't mark until the root of
the render tree (see objectIsRelayoutBoundary) and
thus don't mark all the containing block chains for
paint invalidation. This causes us to leave some
renderer dirty after the paint invalidation phase.

BUG=399206

Review URL: https://codereview.chromium.org/442603003

git-svn-id: svn://svn.chromium.org/blink/trunk@179765 bbb929c8-8fbe-4397-9dbb-9b2b20218538