chore(dialog): switch to OnPush change detection

Switches the dialog container to `OnPush` change detection.

Relates to #5035.

Author: crisbeto

src/lib/dialog/dialog-container.ts

@@ -17,6 +17,7 @@ import {
   EventEmitter,
   Inject,
   Optional,
+  ChangeDetectionStrategy,
 } from '@angular/core';
 import {
   animate,
@@ -50,6 +51,7 @@ export function throwMdDialogContentAlreadyAttachedError() {
   selector: 'md-dialog-container, mat-dialog-container',
   templateUrl: 'dialog-container.html',
   styleUrls: ['dialog.css'],
+  changeDetection: ChangeDetectionStrategy.OnPush,
   encapsulation: ViewEncapsulation.None,
   animations: [
     trigger('slideDialog', [