typo

Author: thomaspink

src/lib/dialog/dialog.ts

@@ -27,7 +27,7 @@ export class MdDialog {
   /** Subject for notifying the user that all open dialogs have finished closing. */
   private _afterAllClosed: Subject<any> = new Subject();
 
-  /** Subject for notifying the user that a dialogs has opened. */
+  /** Subject for notifying the user that a dialog has opened. */
   private _afterOpen: Subject<any> = new Subject();
 
   constructor(private _overlay: Overlay, private _injector: Injector) { }