Write documentation for linking to non-trivial dart entities

It's not documented anywhere how to link to non-trivial Dart entities.

Simple `[prefix.class.member]` references, or relative `[nameInScope]` are easy (which scope is used should be documented, though), but it's not clear how to link to:
* Unnamed constructors: `[C]` refers to the class, the constructor has no other name.
* Operators: `[==]` or `[operator ==]`? `[unary-]`? In another class it's `[C.==]` or `[C.operator==]`? `[[]]` or `[operator[]]` or ?
* Setters: `[foo=]`?

*Can* you refer to a parameter of a function? `[foo.paramName]`? (You *can* refer to it with a relative name in the doc for the function itself, so it's not clear whether you can refer to it from the outside).

Can you refer to a library (if inside it and using its name? If outside it?)

(I've been writing Dart libraries for years, and I can't answer these questions, so please help me) :)