We were passing a sized format and indexing a table which expects unsized.

BUG=angleproject:1384

Change-Id: I69eb8e3d66cfb2178e3a7a4ddb93a54f47bbc938
Reviewed-on: https://chromium-review.googlesource.com/347249Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>