Adds 2 counts to see how often this occurs on the web, both the throwing
version (strict mode), and the no-op sloppy mode case, to help determine
if the proposal at https://github.com/tc39/ecma262/pull/1307 is web
compatible.

This is the V8 side of required changes.
The Chromium-side CL: https://crrev.com/c/1280618

BUG=v8:8175
R=littledan@chromium.org, cbruni@chromium.org, jkummerow@chromium.org, yangguo@chromium.org

Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: Id12336c2e566093bb554b6d4624c9301fbc4a0f7
Reviewed-on: https://chromium-review.googlesource.com/c/1255549
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56706}