We don't need to pass attachment pointers, since they are now
value types, and no longer change their address.

BUG=angleproject:963

Change-Id: I02cdce0886512cc847930f61c5bfb62fc1d7cd1a
Reviewed-on: https://chromium-review.googlesource.com/265938Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>