This is a partial fix to mitigate immediate issues. The code needs some
overhaul to match the recent spec changes.

Drive-by-fix: Partially update comments to match spec

Bug: v8:11949
Change-Id: I6b03d38c758176e29e8951af21c43d030bbb684d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3075360
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76172}