Internal format doesn't play any role in this case, and causes confusion
due to mixing sized and unsized formats resulting in more complicated
code in Chromium.

Bug: angleproject:5538, chromium:1116101
Change-Id: Ie200026f014850053108aa0416e1da15bcda7b84
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2808855
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>