Recomputing the stream offset is relatively cheap now after recent changes. Remove caching it to make the code less complex. TEST=angle_end2end_tests BUG=angleproject:956 Change-Id: Icb9cc4e4ffd685a78b7f8a45958992a471ebb0f5 Reviewed-on: https://chromium-review.googlesource.com/262422Reviewed-by: Nicolas Capens <capn@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org> Tested-by: Olli Etuaho <oetuaho@nvidia.com>
