Popping values from an empty stack is allowed in unreachable code, but
the stack height cannot be negative and stays at 0 instead.

R=clemensb@chromium.org

Bug: chromium:1190291
Change-Id: I84df7ab81ba6f5a9056c8341d88a4c47121363ad
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2778273Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73566}