chai4 regression: instanceOf validation fails for native HTMLElement instances on IE11

[AviVahl]

Starting with chai v4, instanceOf now validates the target as a constructor function.
The assertion resides in: https://github.com/chaijs/chai/blob/master/lib/chai/core/assertions.js#L1604

    var validInstanceOfTarget = constructor === Object(constructor) && (
        typeof constructor === 'function' ||
        (typeof Symbol !== 'undefined' &&
         typeof Symbol.hasInstance !== 'undefined' &&
         Symbol.hasInstance in constructor)
    );

This validation fails on IE11, IE10, and Safari 7 when the constructor is HTMLInputElement.
I'm guessing it's broken for other HTMLElement constructors, and other (old) environments as well.

Sample code which shows the failure:
https://github.com/wix/wix-react-components/blob/master/test/components/number-input.spec.tsx#L17

Failure log:
https://travis-ci.org/wix/wix-react-components/builds/248446200

Notes:

• typeof HTMLInputElement === "object" on IE11.
• <number-input-dom-instance> instanceof HTMLInputElement === true on IE11
• I'm loading core-js/shim to the client, but I've tested the validation a a clean IE11 (about:blank) and it fails even without the shim.

Same assertion worked with chai 3, as there was no validation.

[meeber]

@AviVahl Thanks for the report! I agree that this is a regression in Chai v4 for at least one browser that we actively support: IE11. It's unfortunate that the spec isn't being followed in this case, but I think Chai needs to honor it.

The PR that added this regression is #899, in response to #893. I suspect it's possible to fix this regression while still resolving #893.

Thoughts @lucasfcosta @vieiralucas @shvaikalesh @keithamus?

[shvaikalesh]

We can either special-case HTML constructors or reconsider wrapping instanceof in try/catch and improving error message.

[AviVahl]

Thanks for the fix guys!