DEBUG builds pull in all sorts of instrumentation infrastructure that
leads to larger heaps. The check for intial size is only useful for
release builds.

Bug: v8:6746
Change-Id: I5ab220d21167e69d7fb32c9db68045368c4ef178
R: ulan@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/631876Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47565}