Revert override for desktop GL extensions in gl.xml. Instead override the supported APIs in registry_xml.py, which will transfer to using the canonical gl.xml. Note these are desktop-GL-only extensions that ANGLE exposes in GLES: GL_ARB_sync GL_NV_robustness_video_memory_purge Bug: angleproject:6461 Change-Id: I25778149ecfc3cb4be0aca2104c08273c260c564 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3856648 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jonah Ryan-Davis <jonahr@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Auto-Submit: Jamie Madill <jmadill@chromium.org>