shouldClipCompositedBounds should early exit

There's no reason to evaluate the second condition if we already know what the
result of the function is.

Review URL: https://codereview.chromium.org/181063002

git-svn-id: svn://svn.chromium.org/blink/trunk@167881 bbb929c8-8fbe-4397-9dbb-9b2b20218538