Reland the commit after fixing a bug in FramebufferAttachment. This reverts commit 18fdcbcf. BUG=angleproject:891 Change-Id: I07e08de52bfce8d84d070fc7bc15883009298a4d Reviewed-on: https://chromium-review.googlesource.com/294831Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Corentin Wallez <cwallez@chromium.org>
