Return pointers from check*Allocation. This avoids the need to consult the resource maps twice per bind. It improves performance in applications which call Bind* often. BUG=angleproject:1333 Change-Id: I7b733cc89e50e24a2e38a2eb2dc7fd658d612e27 Reviewed-on: https://chromium-review.googlesource.com/331386 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Zhenyao Mo <zmo@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>