Only use recursion for objects with more than
kMinRangeForMarkingRecursion (8) pointers.

Bug: chromium:651354
Change-Id: Ic71967ef535f6a32268c7097301a313db2335bf8
Reviewed-on: https://chromium-review.googlesource.com/505615Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45326}