Rather than only removing the continuation range for the last return
statement prior to a synthetic return statement, remove the
continuation tracking for whatever statement occurs prior to the
synthetic return.

Bug: v8:10628
Change-Id: Ieb8e393479c9811cf1b9756840bbfdbe7f44a1b8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2280585
Commit-Queue: Benjamin Coe <bencoe@google.com>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68719}