Merge 57922 - 20100420 Justin Schuh <jschuh@chromium.org>...

Merge 57922 - 20100420  Justin Schuh  <jschuh@chromium.org>;

        Reviewed by Adam Barth.

        Invalid cast due to <video> inside <foreignObject> inside <svg> inside <img>
        https://bugs.webkit.org/show_bug.cgi?id=37331

        Added a setting to enable/disable media perpage and have the SVGImage 
        disable media for its dummy page. Also found and fixed a related bad
        cast in the V8 bindings (JSC had a custom wrapper for this already).

        Tests: media/svgasimagewithmediablocked.html
	BUG=40487
TBR=japhet@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=45141