Before I gave the preparser its own zone this was the case. I somewhat
accidentally dropped it when I used set_zone instead; causing large regressions
for certain types of pages.

Bug: chromium:889086
Change-Id: Ib3cf1f926b5c65506c66a97981c4544dccb372aa
Reviewed-on: https://chromium-review.googlesource.com/1245767Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56243}