Respec: Plan to deprecate EdgeHTML support

[saschanaz]

Microsoft won't replace the old Edge soon enough, likely to treat it like IE. We won't support it that long so probably we should get a plan to deprecate it.

So...

Remove Edge support and start using new APIs including Array.prototype.flat:

1. Now
2. After the new Edge gets its first stable release

I wanted to keep supporting Edge when we had no Chromium Edge, but now I have no strong opinion and my life will be completely okay without EdgeHTML support.

cc @marcoscaceres @sidvishnoi

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Collected from discussion below:

• [x] Replace trimLeft, trimRight (#2746)
• [x] Use Object.fromEntries() where applicable (#2761)
• [x] Use Array@flat (#2746)
• [x] Clipboard (#2762)
• [x] [utils@children](https://github.com/w3c/respec/blob/d3ca6fddfc944b7be9bffb27d059926b7e171a53/src/core/utils.js#L770-L796) (#2763)

[sidvishnoi]

What are the pain points in supporting current Edge? What can be refactor or modernise if we remove Edge support? Array.prototype.flat is one, but it doesn't hurt a lot to _polyfill_ it

[saschanaz]

For now the pain is small. Being forced to use .trimLeft() instead of .trimStart(), being unable to use Object.fromEntries() (some code uses .reduce() to do this), etc.

[marcoscaceres]

I think just to be safe, let's wait until first stable. At least then we have a legitimate case to drop support for old Edge, and people who run into trouble have an option to use it (without needing to switch browser vendors).

[saschanaz]

One more pain: a polyfill is required to use navigator.clipboard.writeText(). (We already have one but anyway.)

[sidvishnoi]

Another pain: 'TextEncoder' is not supported, causing entire xref to fail in Edge (image).
TextEncoder is used in xref to create SHA based unique ids.
Version: Microsoft Edge 44.18362.1.0, Microsoft EdgeHTML 18.18362

We can use a polyfill, or use some other way to create hashes (or just deprecate EdgeHTML support :wink:)

[marcoscaceres]

Xref is a W3C feature really, so I’d be fine with us ignoring Edge support.

[sidvishnoi]

I guess we can drop old Edge now

[saschanaz]

Yes, as the new Microsoft Edge is available on https://www.microsoft.com/edge 👍

[marcoscaceres]

Awesome! let's do this!!! What do we need to do??!?

[sidvishnoi]

Collected from comments above:

• [x] Replace trimLeft, trimRight
• [x] Use Object.fromEntries() where applicable
• [x] Use Array@flat
• [ ] Clipboard
• [ ] [utils@children](https://github.com/w3c/respec/blob/d3ca6fddfc944b7be9bffb27d059926b7e171a53/src/core/utils.js#L770-L796)

[sidvishnoi]

I'll be working on Array.flat and trim* parts for now

[sidvishnoi]

I guess we can cleanup utils@children also:
https://github.com/w3c/respec/blob/d3ca6fddfc944b7be9bffb27d059926b7e171a53/src/core/utils.js#L770-L796