Add BGRA formats to glCopyTexSubImage validation. These formats were already accepted by glCopyTexImage and allow glCopyTexSubImage to work on the default framebuffer for D3D9 and D3D11. BUG=angleproject:2027 Change-Id: I5d8b839ae2c69e1e8381aa011df6223e18afb308 Reviewed-on: https://chromium-review.googlesource.com/493803 Reviewed-by: Jamie Madill <jmadill@chromium.org>