ParserBase::ParseClassLiteral and BaseConsumedPreparseData::RestoreDataForScope
both declare the class variable, but the logic is so complex
that they sometimes ended up both declaring it.

This is further complicated by some of the variable values (esp.
inner_scope_calls_eval_) potentially changing in between, so we can't
just redo the same logic any more.

Forcefully make it work by making RestoreDataForScope declare the variable
iff ParseClassLiteral didn't.

Bug: chromium:1245870
Change-Id: I777fd9d78145240448fc25709d2b118977d91056
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3140596
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76654}