The mask should cover the sign (1 bit), exponent (11 bits) and quiet bit (1 bit) of significand, total of 13 bits. The old mask only covered 9 bits.

Change-Id: I6ec402b4cec34978eac8fa3e5452ad22540a93ce
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1726984Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63015}