Refactor Texture::setImage and subImage to use gl::Error objects. BUG=angle:520 Change-Id: Ib43ace0fbdab59086ae4314cce139636d9045e65 Reviewed-on: https://chromium-review.googlesource.com/216644 Reviewed-by: Shannon Woods <shannonwoods@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>