Final preparations for GStreamer on Windows.

Final preparations for GStreamer on Windows.
https://bugs.webkit.org/show_bug.cgi?id=125958

Patch by Alex Christensen <achristensen@webkit.org> on 2013-12-19
Reviewed by Benjamin Poulain.

Source/WTF:

* WTF.vcxproj/WTFDebugWinCairo.props:
* WTF.vcxproj/WTFReleaseWinCairo.props:
Include WinCairo.props.
* wtf/Platform.h:
Use GLib and GStreamer on WinCairo with video.

WebKitLibraries:

* win/tools/vsprops/FeatureDefinesCairo.props:
Removed duplicate ENABLE_VIDEO_TRACK definition.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@160855 268f45cc-cd09-0410-ab3c-d52691b4dbfc