This DCHECK is incorrect in no-snapshot builds because we can run 
garbage collection while deserializing the snapshot.

Bug: v8:6559, v8:6557
Change-Id: I0b8456ee19443f796889656952b236ff40b1e2fb
Reviewed-on: https://chromium-review.googlesource.com/600367Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Maya Lekova <mslekova@google.com>
Cr-Commit-Position: refs/heads/master@{#47130}