Render generic type parameters in functions.

[kallentu]

Added generic type parameters to function parameters, fixing #3452.

For that issue's example, it'd show as the following now.

// Before: extractIterableTypeArgument(Iterable iterable, Object? extract()) → Object?
extractIterableTypeArgument(Iterable iterable, Object? extract<T>()) → Object?

@srawlins
Wondering if we should revisit the function format and make it Object? Function<T>() extract instead of Object? extract<T>()? This CL isn't for that, but it wouldn't be too hard to make that change.

• Renamed some tests in parameter_test.dart because I was itching to do so.
• The two new tests added are test_formalParameter_generic_method and test_formalParameter_generic_topLevelFunction.

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[srawlins]

Very nice! Nice test refactoring.

[srawlins]

Wondering if we should revisit the function format and make it Object? Function<T>() extract instead of Object? extract<T>()?

I think I would be in favor of this. I can see supporting one of two designs:

• Always display the new format.
• Always display what is in the source code; if they wrote the old school format, support that. There are plenty of cases in the Dart SDK at least that use the old school format, like Future.then. I'm not sure if it's intentional, but if it is 🤷 maybe leave it that way in dartdoc too.

[kallentu]

I'll look into it in my free-time, but if we could, I think maybe it'd be good to display what's in the source code.

I'll make an issue for this.