This will randomly break compilation units that don't happen to #define
DCHECK before v8-util.h is included.

BUG=chromium:688155

Change-Id: I7abdaf87c8bb7aca995d9e6e7ef8b4faff0dc50c
Reviewed-on: https://chromium-review.googlesource.com/447002Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43455}