Bind native GL attributes to match the locations in gl::Program. Simplifies a lot of logic when we don't have to maintain mappings between the driver and gl-layer locations. BUG=angleproject:882 BUG=angleproject:1123 Change-Id: Ia94257a322f768fdfa3167000a46a0715820ef4d Reviewed-on: https://chromium-review.googlesource.com/295231 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>