anchor.diff:        var p = mixinProperties[i];
         prototype[p] = mixinPrototype[p];
       }
  -    // Since this is a mixin application the constructor will actually never
  -    // be invoked. We only use its prototype for the application's subclasses. 
  -    var constructor = function() {};
  -    return constructor;
     }
   
     function determinePrototype(descriptor) {
  
positive.code:     return constructor;
    }
  
    function compileMixinConstructor(name, prototype, descriptor) {
      // $mixinFormatDescription.
      var mixinName = descriptor[2];
      var mixinHolderIndex = descriptor[3];
      var mixin = holders[mixinHolderIndex][mixinName].ensureResolved();
      var mixinPrototype = mixin.prototype;
  
  
negative.code:       MixinApplication mixin = cls;
        elements.add(js.string(mixin.mixinClass.name));
        elements.add(js.number(mixin.mixinClass.holder.index));
        if (cls.isDirectlyInstantiated) {
          elements.add(_generateConstructor(cls));
        }
      } else {
        elements.add(_generateConstructor(cls));
      }
  