Support D3D texture share handles in the OpenGL backend on Windows. BUG=angleproject:1144 Change-Id: Ideb0ed306ae8417f53b813745ced43002d028126 Reviewed-on: https://chromium-review.googlesource.com/461271 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>