A few methods (Free, TryFindInNode, SearchForNodeInList) were
identical in each FreeList implementation, yet redefined each
time. They are now defined in the class FreeList, and inherited by
subclasses (which can override them if needed).

Additionnaly, GuaranteedAllocatable in FreeListFast and FreeListMany
were wrong in their respective last case; they are now fixed.

Consequently to fixing FreeListMany::GuaranteedAllocatable,
FreeListMany was slightly reworked:
  - The last freelist is now fully searched during allocation (rather
    than just looking at its first element like for the other
    freelists).

Bug: v8:9329
Change-Id: Ic86ade3b1acaa2ca91cce17bd6822ec12aa594d9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1706478Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Darius Mercadier <dmercadier@google.com>
Cr-Commit-Position: refs/heads/master@{#62845}