The visitor was removing pages while at the same time iterating them on
NormalPagedSpace.

Removing all pages at once is safe and should also be faster.

Bug: chromium:1056170
Change-Id: I56eedf6f09498f126cb09238e01962b48e75b657
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2190427Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67687}