anchor.diff:                selector.argumentCount, selector.namedArguments);
             if (!selector.appliesUnnamed(member, compiler.world)) continue;
             if (untypedSelectors.add(selector)) {
  -            // TODO(ahe): Is the last argument to [addParameterStub] needed?
  -            addParameterStub(member, selector, defineStub, new Set<String>());
  +            addParameterStub(member, selector, defineStub);
             }
           }
         }
  
positive.code:       for (Selector selector in selectors) {
          if (!selector.appliesUnnamed(member, compiler.world)) continue;
          if (untypedSelectors.add(selector.asUntyped)) {
            // TODO(ahe): Is the last argument to [addParameterStub] needed?
            addParameterStub(member, selector, defineStub, new Set<String>());
          }
        }
      }
  
negative.code:    */
    void addParameterStub(FunctionElement member,
                          Selector selector,
                          AddStubFunction addStub) {
      FunctionSignature parameters = member.functionSignature;
      int positionalArgumentCount = selector.positionalArgumentCount;
      if (positionalArgumentCount == parameters.parameterCount) {
  