Fix crash when using `instanceof HTMLElement` in some environments

[RobinMalfait]

This PR fixes an issue where in some environments where HTMLElement is not available (on the server) and AG Grid is used, we crashed.

This happens because the HTMLElement is polyfilled to an empty object. This means that the typeof HTMLElement !== 'undefined' check passed, but the v instanceof HTMLElement translated to v instanceof {} which is invalid and resulted in a crash...

This PR solves it by checking for exactly what we need, in this case whether the outerHTML property is available.

Alternatively, we could use return v?.outerHTML ?? v, but not sure if that's always safe to do.

Fixes: #3471

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[RobinMalfait]

@thecrypticace thoughts on this solution compared to v?.outerHTML ?? v?

[thecrypticace]

Honestly I think I'd use v?.outerHTML ?? v — just throw in a comment as to why because I know we'll forget.

Aside: If AG Grid is polyfilling HTMLElement to {} and not at least function HTMLElement() {} that is absolutely a bug in AG Grid.

[thecrypticace]

I guess the only reason it wouldn't be safe is if String.prototype.outerHTML was defined right? But that would be really bizarre. So I guess we could check for an object. I'm fine with either honestly.

[RobinMalfait]

Aside: If AG Grid is polyfilling HTMLElement to {} and not at least function HTMLElement() {} that is absolutely a bug in AG Grid.

100% agree, if they do that for test code in their own tests that's one thing. But this is in production, so definitely not ideal.

Either way, with this PR the code is a bit cleaner as well so why not..