anchor.diff:        DartType elementType = _dynamicType;
         NodeList<TypeAnnotation> arguments = typeArguments.arguments;
         if (arguments != null && arguments.length == 1) {
  -        DartType argumentType = _getType(arguments[0]);
  +        DartType argumentType = arguments[0].type;
           if (argumentType != null) {
             elementType = argumentType;
           }
  
positive.code:     if (typeArguments != null) {
        if (typeArguments.length == 1) {
          (node as SetOrMapLiteralImpl).becomeSet();
          var elementType = _getType(typeArguments[0]) ?? _dynamicType;
          _recordStaticType(
            node,
            _typeProvider.setElement.instantiate(
  
negative.code:         return;
        } else if (typeArguments.length == 2) {
          (node as SetOrMapLiteralImpl).becomeMap();
          var keyType = typeArguments[0].type;
          var valueType = typeArguments[1].type;
          _recordStaticType(
            node,
            _typeProvider.mapElement.instantiate(
  