This CL fixes the ScopeIterator when it's created for a stack frame
that represents the script scope. For example the following script:
```
function foo() { debugger; }
foo();
```
Then a ScopeIterator created for the second stack frame (`foo()`)
should not a create a blocklist. This is somewhat a special case,
since the closure_scope_/start_scope_ are the SCRIPT_SCOPE.
Note that the debug-evaluate code can't run into this scenario as
we would never iterate far enough to actually trigger block list
calculation. Nevertheless, since it's possible to create a
`ScopeIterator` that could run into this scenario, we guard
against it.
R=jarin@chromium.org
Bug: chromium:1363561
Change-Id: I0677c257d41c9af5ffc38d390f58997da20fd069
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3960568
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83754}
0a66c1b365