There are cases where DeclareEvalVar can fail to create a variable, in
particular when the declaration scope is not extensible. Throw an error
in such cases.

Fixed: chromium:1145119
Change-Id: I6260f570570c4d7801231bdb5f6724f3734444fd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3295348
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78017}