Capture: Write captured context for empty frames When a frame is empty, still write the captured context for that frame because the index file will contain the frame file, and the replay will execute the according swapbuffer so that the replay will query the context serialization when testing trace correctness. With that enable RobustResourceInitTest.SurfaceInitializedAfterSwap/* for capture/replay. Bug: angleproject:5939 Change-Id: Ib280d55f739cc2bb8d2da0919e98c37a2cd576ba Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2987991 Commit-Queue: Gert Wollny <gert.wollny@collabora.com> Reviewed-by: Cody Northrop <cnorthrop@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>