strict mode compatibility

[ef4]

This fixes #1557 by adopting globalThis, and polyfilling it for environments that don't implement it yet via @ungap/global-this.

[rwjblue]

In general, we need to avoid poly filling in tests only. This PR as it stands could enable your tests to pass in circumstances that would not work when QUnit itself wasn't loaded. For example, imagine your application code could access globalThis but forgot to bring the polyfill along with it. With the current implementation in this PR your tests would pass still, but if you deployed to environments without a naturally available globalThis your application would crash.

Since the code for the polyfill is sooo small, it might just be easier to put it alongside our promise polyfill instead of using @ungap/global-this (which mutates the environment to define globalThis).

I think you could get away with something like this in lib/global-this-polyfill.js, then import that throughout:

/*
https://github.com/ungap/global-this/blob/v0.4.4/esm/index.js

Copyright (c) 2020, Andrea Giammarchi, @WebReflection

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.

-------

Patches for use in QUnit:

- 2021-02-25: Export as module only, don't change global scope as QUnit must not
  affect the host context (e.g. people may test their application intentionally
  with different or no polyfills and we must not affect that).

*/

let foundGlobalThis;

(function (Object) {
  if (typeof globalThis === "object") {
    foundGlobalThis = globalThis;
  } else {
    this
      ? get()
      : (Object.defineProperty(Object.prototype, "_T_", {
          configurable: true,
          get: get,
        }),
        _T_);

    function get() {
      foundGlobalThis = this || self;
      delete Object.prototype._T_;
    }
  }
})(Object);

export default foundGlobalThis;

[ef4]

This now incorporates Robert's feedback to no longer leak the polyfill.

[rwjblue]

@Krinkle - Any chance you could review? The strict mode breakage was introduced in 2671d3f (moving to import global from 'global') due to the changes made in 484d396 (specifically the fake global module added in the rollup.config.js).

[Krinkle]

Tested locally in Firefox, and in IE9-11 via BrowserStack.

[rwjblue]

Thank you @Krinkle!

[22a]

Thanks for this fix! Is there any ETA on when it will be bundled into an npm release?

[Krinkle]

@22a Tomorrow, or else in the weekend.

[22a]

@Krinkle Wonderful, thank you!