The fuzzer was generating cases where floating point constants would
someone return as valid when they were beyond max float. I was unable
to reproduce this in a standalone test, but confirmed this check
fixes the fuzzer error.

BUG=660702

Change-Id: I9e6b883958013638ea509e38b30e812a9e74fbc1
Reviewed-on: https://chromium-review.googlesource.com/406268Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>