Reviewed by Darin.
        
        Trigger media load on on src attribute changes as specified in new HTML5 draft.

        Tests: media/video-src-change.html
               media/video-src-remove.html
               media/video-src-set.html

        * html/HTMLMediaElement.cpp:
        (WebCore::HTMLMediaElement::attributeChanged):
        * html/HTMLMediaElement.h:

LayoutTests:

        Reviewed by Darin.
        
        Tests for media src attribute changes.

        * media/video-src-change-expected.txt: Added.
        * media/video-src-change.html: Added.
        * media/video-src-remove-expected.txt: Added.
        * media/video-src-remove.html: Added.
        * media/video-src-set-expected.txt: Added.
        * media/video-src-set.html: Added.
        * media/video-test.js:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@27480 268f45cc-cd09-0410-ab3c-d52691b4dbfc