Clear absolute clip rects when transform changes

A layer's absolute clip rects are no longer valid when its
transform or the transform of an ancestor changes, since the
layer moves in absolute space. This CL clears the absolute
clip rects of a layer and its descendants when the layer's
transform changes.

BUG=246965

Review URL: https://codereview.chromium.org/334373002

git-svn-id: svn://svn.chromium.org/blink/trunk@176432 bbb929c8-8fbe-4397-9dbb-9b2b20218538