Previously, ParseInfo would create a script (with CreateScript) based on
its flags, and then set its own flags based on that created script. This
created a weird circular dependency for some of those flags, and
sometimes we would have valid flags before script creation (main thread
compile), while other times not (streaming compile).

Now we set the ParseInfo flags manually and uniformly before script
creation, and check that they match the created script after it has been
created.

Bug: v8:10314
Change-Id: Ife886c77727cd228c944a4f97369a3e6365d8219
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2093433
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66648}