R=titzer@chromium.org
TEST=mjsunit/regress/wasm/regress-799952
BUG=chromium:799952

Change-Id: Idb4a1938cc04f2f5b1ea33ba390c5917fea2c0c1
Reviewed-on: https://chromium-review.googlesource.com/1075967Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53402}