fix fuzz test that exceeds numeric limit

The extreme values here exceed an internal test that expects
computed numbers to be less than MAX_FLT. Use MAX_DBL instead.

R=mmoroz@chromium.org
TBR=reed@google.com
BUG=624346
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2103903004

Review-Url: https://codereview.chromium.org/2103903004
3 files changed