anchor.diff:      HashSet<Element> elements = new HashSet<Element>();
       _add(elements, firstElement);
       _add(elements, secondElement);
  -    return new List.from(elements);
  +    return elements.toList(growable: false);
     }
   }
   
  
positive.code:           prefixes.add(prefix);
          }
        }
        _prefixes = prefixes.toList();
      }
      return _prefixes;
    }
  
negative.code:       implicitConstructor.enclosingElement = this;
        implicitConstructor.type = new FunctionTypeImpl(implicitConstructor);
        return implicitConstructor;
      }).toList(growable: false);
    }
  
    PropertyAccessorElement _internalLookUpConcreteGetter(
  