Along with HeapNumberBase and MutableHeapNumber, of course.

Bug: v8:5402
Change-Id: I14a7f8052de3839cad36bb7e4ebb6da38b2ac096
Reviewed-on: https://chromium-review.googlesource.com/c/1379884
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58293}