code: function makeCtor (className) {
          function constructor () {
              // Opera has some problems returning from a constructor when Dragonfly isn't running. The || null seems to
              // be sufficient to stop it misbehaving. Known to be required against 10.53, 11.51 and 11.61.
              return this.constructor.apply(this, arguments) || null;
          }
          //<debug>
          if (className) {
              constructor.displayName = className;
          }
          //</debug>
          return constructor;
      }
docs: Creates a constructor that has nothing extra in its scope chain.