This makes it more explicit what we're actually parsing and allows us to omit
unnecessary checks.

Change-Id: I3e22ab4af0f23cee51cb689dd6377565e42f9bad
Reviewed-on: https://chromium-review.googlesource.com/c/1260943Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56377}