Make all drawable rectangles in Layer3DView general.

Review URL: https://codereview.chromium.org/391983004

Review URL: https://codereview.chromium.org/391983004

git-svn-id: svn://svn.chromium.org/blink/trunk@178281 bbb929c8-8fbe-4397-9dbb-9b2b20218538