Allow MapResource to return context loss GL error Returns an OOM error to avoid query the context for status should Map fail. BUG=angleproject:2284 Change-Id: I4d35ef05c76fcc69bdab19f88c39a415d13ee116 Reviewed-on: https://chromium-review.googlesource.com/837519 Commit-Queue: Yuly Novikov <ynovikov@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org>