Fix a rendering bug when frames have no dirty rect on display list mode.

In the current implementation, finalizeFrameInternal() is returned early when
the image buffer doesn't have dirty rect. Even so we should transfer a state
stack to next canvas.

BUG=392614

Review URL: https://codereview.chromium.org/588403003

git-svn-id: svn://svn.chromium.org/blink/trunk@182556 bbb929c8-8fbe-4397-9dbb-9b2b20218538