This CL changes the {ScopeIterator} to re-parse the whole script instead
of just the immediate function. The result are accurate parent scopes,
which will enable better variable lookup for debug evaluation.

Drive-by: Remove unused IGNORE_NESTED_SCOPES ScopeIterator::Option and
refactor ScopeIteartor::Next.

Change-Id: I6cb9d303fe5f84da4f4b11c6e2057f07c232316c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771785Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63592}