Reviewed by Darin Adler.

        <rdar://problem/6438177> QTMoviePreferredTransformAttribute only supported on SnowLeopard
        <rdar://problem/6872468> QTMovieOpenForPlaybackAttribute only supported on SnowLeopard

        QTMoviePreferredTransformAttribute and QTMovieOpenForPlaybackAttribute are not supported
        on Tiger or Leopard.

        * html/HTMLMediaElement.cpp:
        (WebCore::HTMLMediaElement::setNetworkState): Remove invalid ASSERT.

        * platform/graphics/mac/MediaPlayerPrivateQTKit.mm:
        (WebCore::MediaPlayerPrivate::createQTMovie): Only request QTMoviePreferredTransformAttribute
        when !BUILDING_ON_TIGER and !BUILDING_ON_LEOPARD.
        (WebCore::MediaPlayerPrivate::cacheMovieScale): Only ask for QTMovieOpenForPlaybackAttribute 
        when !BUILDING_ON_TIGER and !BUILDING_ON_LEOPARD,



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@43622 268f45cc-cd09-0410-ab3c-d52691b4dbfc