Per ECMA-262 25.5.3.2, step 5.e: |generatorBody| execution ends with a normal completion.

Bug: v8:9050
Change-Id: If2ecc7d104e0b905a4b2b4695522be740e0d0349
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1611011Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Joshua Litt <joshualitt@google.com>
Cr-Commit-Position: refs/heads/master@{#61589}