Set video src from script, not from the element attribute. This

    Set video src from script, not from the element attribute. This
        guarantees load events do not fire before event listeners are registered.
        This change does not affect test results.

        * media/progress-event.html:
        * media/video-autoplay.html:
        * media/video-buffered.html:
        * media/video-currentTime-set.html:
        * media/video-currentTime-set2.html:
        * media/video-currentTime.html:
        * media/video-dom-autoplay.html:
        * media/video-error-abort.html:
        * media/video-error-does-not-exist.html:
        * media/video-load-networkState.html:
        * media/video-load-readyState.html:
        * media/video-no-autoplay.html:
        * media/video-seekable.html:
        * media/video-seeking.html:
        * media/video-size.html:
        * media/video-src.html:
        * media/video-start.html:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@27990 268f45cc-cd09-0410-ab3c-d52691b4dbfc