Revert "Make FramebufferAttachmentObject not refcountable" BUG= This reverts commit 19ba57469aa02074d094a9aef104f84d0b6d881e. Change-Id: I5dce6c8a81570e22affbcaf32183a97c97849718 Reviewed-on: https://chromium-review.googlesource.com/293351 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Tested-by: Corentin Wallez <cwallez@chromium.org>