The Scavenger is the only consumer of free list entries besides MC
evacuation and pretenured allocations. Make use of all size classes for
allocation.

Bug: chromium:738865
Change-Id: Ieb62c01b41f2aa62222efac91dde4dce2127ff70
Reviewed-on: https://chromium-review.googlesource.com/580409Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46812}