A spec change to simplify IsRegExp has been proposed:

https://github.com/tc39/ecma262/pull/1318

This CL adds use counters for cases in which the spec change would
alter behavior:

1. o[@@match] is trueish but o is not a JSRegExp
2. o[@@match] is falseish (but not undefined) and o is a JSRegExp

This is the V8 side of required changes.
The Chromium-side CL: https://crrev.com/c/1360730

Drive-by: TNodeify IsRegExp.

Tbr: yangguo@chromium.org
Bug: v8:8522
Change-Id: I3766e02977f256a80d0e59472d3bafa9c692af9e
Reviewed-on: https://chromium-review.googlesource.com/c/1360630Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58064}