Surface: Use ref count for bindTexImage. This frees up one more use of ProxyContext. It will also keep the bound surface alive until it is unbound from a Texture. Two usages of the proxy context remains. * DisplayD3D::restoreLostDevice. * Display::destroyImage. Bug: angleproject:2714 Change-Id: Ied72c6ebe060d7fc1743b3313e162d540fcbfe02 Reviewed-on: https://chromium-review.googlesource.com/1137878 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>