R=sigurds@chromium.org
TEST=mjsunit/wasm/module-memory

Change-Id: I30b52a09d8655340199dc449aaa91e6a351e2111
Reviewed-on: https://chromium-review.googlesource.com/1188567Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55410}