[tests] Add older browser compatibility tests

[DmitrySharabin]

Supported browsers

macOS

• Chrome 89+
• Firefox 90+
• Safari 15.4+

Windows

• Chrome 89+
• Firefox 90+

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[LeaVerou]

Rewriting hTest with PostCSS seems ...overkill. The rest seems fine.

[DmitrySharabin]

Rewriting hTest with PostCSS seems ...overkill. The rest seems fine.

OK, I switched to an external stylesheet that fixes broken styles.

[LeaVerou]

I ...still don't think we want to be stubbing in stylesheets for hTest. If people want to test in browsers that hTest doesn't support, I think it's totally valid that they're on their own.

[DmitrySharabin]

I ...still don't think we want to be stubbing in stylesheets for hTest. If people want to test in browsers that hTest doesn't support, I think it's totally valid that they're on their own.

That's much easier. Oof 😅

One thing that bothers me a bit. Take a look at how this page looks in older browsers:

Do we probably need some styles, though? We don't even know whether the tests pass. 🤷‍♂️ What do you think?

[LeaVerou]

You have to draw the line somewhere. Do you know how crappy this page looks in IE6? 😅

[DmitrySharabin]

I am down to move the responsibility to the developers using these tests in older browsers. 😅

Let me delete redundant code real quick.