Windows may be the last platform that uses the old style media controls. Port Windows to the new-style controls similar to how WebKitGTK/WPE was ported recently. (see bug 182502)
<rdar://problem/94552653>
It looks like the cpp/h and IDL files in WebCore/Modules/mediacontrols are still used by the modern-media-controls. I'm doing an experiment where I delete the old css/js files and try to run tests on both Mac and Windows. I suspect (and hope) everything may "just work"