Adding or changing any of box-shadow, outline, or border-image-outset does not need a layout..

.. so just require a paint invalidation and ensure visual overflow gets recomputed.

There is an optimization that throttles paint invalidations on an element when
the children have just been laid out - now that we avoid this layout we want
to continue throttling these repaints. I will address this in a follow-up.

BUG=396825

Review URL: https://codereview.chromium.org/561303002

git-svn-id: svn://svn.chromium.org/blink/trunk@183698 bbb929c8-8fbe-4397-9dbb-9b2b20218538