Mostly these calls pass through to BufferStorage.

BUG=angle:565
Change-Id: I38ab7d4f49bfad940773428f5bb330de55d3f573
Reviewed-on: https://chromium-review.googlesource.com/187080Reviewed-by: Nicolas Capens <nicolascapens@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>