This replaces Heap::InNewSpace with Heap::InYoungGeneration and
fixes tests that are sensitive to page size.

Bug: chromium:852420
Change-Id: I32b1eafb45813ea3bdcbda075f9e6156aaf4c5e3
Reviewed-on: https://chromium-review.googlesource.com/c/1475766Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59647}