The main motivation is to get bug reports / crashes from Canary.

This commit is expected to break all kinds of things! The most typical failure
modes are crashes, CHECK failures and JavaScript executing incorrectly.

BUG=v8:5516

Change-Id: Ifa02b420ad4e8eda46002b334bed2665c8ceeeb2
Reviewed-on: https://chromium-review.googlesource.com/623751Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47502}