Ensure ABP UI Edge 15 compatibility

[agiammarchi]

Even Microsoft Virtual Machines ship with Edge 16 already installed by default, and it's also difficult to setup remote VMs (i.e. webmate) to connect to local folders for debugging purpose.

We need to be sure our JS, as well as our CSS and layout in general, works as meant/expected on Edge 15 since this is still part of our target browsers.

Environment

Windows 10 - Edge 15

Observed behaviour

There are common JavaScript patterns we use, such for/of loops, that throws error in Edge 15 because of the missing Symbol.iterator in the NodeList.prototype.

This is just one error we don't easily spot via VMs and Edge 16, the current default base for Edge, but there might be other JS or CSS issues with the version 15.

Expected behaviour

If we say we target Edge 15, it should just work with all of our code, without throwing errors here or there.

[agiammarchi]

a for/of failing on node list selection

[agiammarchi]

After various tests / checks I've concluded that Edge 15 and Chrome < 51 are actually covered by our code base.

While I'd suggest to better polyfill the absence of Symbol.iterator through this loop instead:

  // Workaround since HTMLCollection, NodeList, StyleSheetList, and CSSRuleList
  // didn't have iterator support before Chrome 51.
  // https://bugs.chromium.org/p/chromium/issues/detail?id=401699
  for (const Class of [HTMLCollection, NodeList, StyleSheetList, CSSRuleList])
  {
    if (!(Symbol.iterator in Class.prototype))
      Object.defineProperty(Class.prototype, Symbol.iterator, {
        configurable: true,
        writable: true,
        value: Array.prototype[Symbol.iterator]
      });
  }

I don't think this ticket should be further investigated.

Summary

The polyfill.js we have in UI uses (copy & paste) same polyfill that adblockpluschrome repository bundles, and ship, in production.

Accordingly, all those collections that would otherwise fail in Edge 15 and Chrome < 51 are patched.

On top of that, all recently changed CSS seems to work just as fine in both Edge 15 and Chrome 49.

[agiammarchi]

For clarity sake, even if I've investigated everything was fine in Edge, the initial ticket was technically invalid.

We still need to be sure we all grant Edge 15 works when we implement new features, but that's another story.