This fixes a failure in test/mjsunit/regress/regress-crbug-491062.js.

R=dstence@us.ibm.com, michael_dawson@ca.ibm.com, svenpanne@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1174693002

Cr-Commit-Position: refs/heads/master@{#28924}