Remove extra call to scheduleRelayout in Document::setParsing

There's no particular reason to schedule a layout when we call
Document::setParsing(false). We'll schedule a layout when the last stylesheet
loads, which is a better signal that it's time to put up the first frame.

R=esprehn@chromium.org

Review URL: https://codereview.chromium.org/166403002

git-svn-id: svn://svn.chromium.org/blink/trunk@167180 bbb929c8-8fbe-4397-9dbb-9b2b20218538