title: Property 'do' does not exist on type 'Observable<IProduct[]>'
body: <p>After upgrading to Angular 6.0 and Rxjs to 6.0 I receive the following compilation error:</p>
  
  <p><code>Property 'do' does not exist on type 'Observable'.</code></p>
  
  <p>Here is the code:</p>
  
  <pre><code>import { Observable, of } from 'rxjs';
  import 'rxjs/add/operator/do';
  import 'rxjs/add/observable/throw';
  import 'rxjs/add/operator/catch';
  import { IProduct } from './product';
  
  @Injectable()
  export class ProductService { 
      constructor(
          private product: IProduct)
      {         
      }
  
      getProduct = () =&gt; { 
          return product.products
              // error on next line
              .do(data =&gt; console.log('All:' + JSON.stringify(data)))
              .catch(this.handleError);
      }
  
      private handleError(err: HttpErrorResponse) { 
          console.log(err.message);
          return Observable.throw(err.message);        
      }
  }
  </code></pre>
  
  <p>Any idea?</p>