function ThrowObservable(error, scheduler) {
      this._error = error;
      this._scheduler = scheduler;
      __super__.call(this);
    }
Returns an observable sequence that contains a single element, using the specified scheduler to send out observer messages.
 There is an alias called 'just' or browsers <IE9.
@param {Mixed} value Single element in the resulting observable sequence.
@param {Scheduler} scheduler Scheduler to send the single element on. If not specified, defaults to Scheduler.immediate.
@returns {Observable} An observable sequence containing the single specified element.