anchor.diff:  }
   
   /// Returns the mirror for the root Object type.
  -ClassMirror get objectMirror {
  -  if (_objectMirror == null) {
  -    _objectMirror = currentMirrorSystem()
  -        .libraries[Uri.parse('dart:core')]
  -        .classes[const Symbol('Object')];
  -  }
  -  return _objectMirror;
  -}
  -ClassMirror _objectMirror;
  +ClassMirror get objectMirror => reflectClass(Object);
   
   // TODO(nweiz): clean this up when issue 13248 is fixed.
   MethodMirror getConstructor(ClassMirror classMirror, String constructor) {
     var name = new Symbol("\${MirrorSystem.getName(classMirror.simpleName)}"
         ".\$constructor");
  -  return classMirror.constructors[name];
  +  var candidate = classMirror.declarations[name];
  +  if (candidate is MethodMirror && candidate.isConstructor) return candidate;
  +  return null;
   }
   
   // TODO(nweiz): get rid of this when issue 12439 is fixed.
  
positive.code: 
  // TODO(nweiz): get rid of this when issue 12826 is fixed.
  /// Returns whether or not [mirror] is an abstract class.
  bool isAbstract(ClassMirror mirror) => mirror.members.values
      .any((member) => member is MethodMirror && member.isAbstract);
  
  /// Converts [transformerOrGroup] into a serializable map.
  
negative.code: 
    // TODO(nweiz): if no valid transformers are found, throw an error message
    // describing candidates and why they were rejected.
    return mirrors.libraries[uri].declarations.values.map((declaration) {
      if (declaration is! ClassMirror) return null;
      var classMirror = declaration;
      if (classMirror.isPrivate) return null;
      if (isAbstract(classMirror)) return null;
      if (!classIsA(classMirror, transformerClass) &&
  