Fix Repaint-After-Layout after partial layout removal.

When the partial layout code was removed this changed the conditional
for triggering repaintTree from m_doFullRepaint || !partialLayout.isStopping()
to just m_doFullRepaint. This caused repaint to not happen in a lot of cases
because, typically, !paritalLayout.isStopping() was true and would trigger
repaintTree. I don't think we need the check at all and should be
unconditionally triggering repaintTree and using the information from layout to
determine what repaints.

BUG=283623,320139

Review URL: https://codereview.chromium.org/206413003

git-svn-id: svn://svn.chromium.org/blink/trunk@169656 bbb929c8-8fbe-4397-9dbb-9b2b20218538