The preparser doesn't support extension parsing so always return false
there, and move the field to the parser instead.

Change-Id: Ie9ad0bd710858120467eb709ec92e59b38eaffba
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3009214Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75588}