message: refactor(ignoreElements): removed redundant noop
  Minor optimization.
  We don't need to call any kind of `noop` function, simply do not call anything.
diff: import { Observable } from '../Observable';
  import { Operator } from '../Operator';
  import { Subscriber } from '../Subscriber';
  -import { noop } from '../util/noop';
  import { MonoTypeOperatorFunction } from '../interfaces';
  /**
  @@ -33,6 +32,6 @@ class IgnoreElementsOperator<T, R> implements Operator<T, R> {
  */
  class IgnoreElementsSubscriber<T> extends Subscriber<T> {
  protected _next(unused: T): void {
  - noop();
  + // Do nothing
  }
  }
  