An upcoming CL will remove the COLLECT_NON_LOCALS support of the
ScopeIterator. The DebugStackTraceIterator uses the list of non-locals
to restore the receiver for arrow functions.

This CL extracts the relevant logic into a small helper and calls
it directly.

Change-Id: Ia396fd599e41ca65810497d2f5228619cfdf7cc4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1795347Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63645}