Issue paint invalidations *before* and after changing offsetFromRenderer
and reconfiguring the squashing GraphicsLayer.

Previously we were issuing them only after.

BUG=385103

Review URL: https://codereview.chromium.org/345653002

git-svn-id: svn://svn.chromium.org/blink/trunk@176466 bbb929c8-8fbe-4397-9dbb-9b2b20218538