Revert "Make compositingState explicit"

This reverts
https://src.chromium.org/viewvc/blink?revision=159068&view=revision
which seems to cause bunch of ASSERTION FAILED:
  compositingState() == HasOwnBackingButPaintsIntoAncestor ||
  compositingState() == PaintsIntoOwnBacking
    at RenderLayer.h(473)

TBR=enne@chromium.org
BUG=261605
NOTRY=true

Review URL: https://codereview.chromium.org/26431002

git-svn-id: svn://svn.chromium.org/blink/trunk@159080 bbb929c8-8fbe-4397-9dbb-9b2b20218538