Use recursion scope only for nullable references in the
GenerateRef function. We declare the recursion scope as
an optional and only initialize it if the reference type
is nullable.

Bug: v8:11954, chromium:1270126
Change-Id: I1548290cc9d48167f6fd56ff653744d472f65635
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3284894Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
Commit-Queue: Maria Tîmbur <mtimbur@google.com>
Cr-Commit-Position: refs/heads/main@{#77943}