dartdoc shows the wrong parameters for new-style generic function types

[jcollins-g]

A function that looks like this:

/// A typedef with the new style generic function syntax.
typedef NewGenericTypedef<T> = List<S> Function<S>(T, int, bool);

is currently documented as having parameters (T, T, T).

This is caused by analyzer producing ParameterElementImpls that compare equally to each other, subverting dartdoc's internal object cache. dart-lang/sdk#30146

[jcollins-g]

This also occurs for types created as functions with parameters defined outside of typedefs, for example:

  void Function(T1, T2) bindBinaryCallbackGuarded<T1, T2>(
      void callback(T1 argument1, T2 argument2));

will be documented as:

void Function(T1, T1) bindBinaryCallbackGuarded....

[jcollins-g]

Fixed in #1524, though through a hacky workaround (disabling Dartdoc's object cache for parameters).