Remove redundant element roles.

Author: crisbeto

src/lib/dialog/dialog-content-directives.ts

@@ -23,10 +23,7 @@ export class MdDialogClose {
  * Title of a dialog element. Stays fixed to the top of the dialog when scrolling.
  */
 @Directive({
-  selector: '[md-dialog-title], [mat-dialog-title]',
-  host: {
-    role: 'heading'
-  }
+  selector: '[md-dialog-title], [mat-dialog-title]'
 })
 export class MdDialogTitle { }
 
@@ -35,10 +32,7 @@ export class MdDialogTitle { }
  * Scrollable content container of a dialog.
  */
 @Directive({
-  selector: '[md-dialog-content], md-dialog-content, [mat-dialog-content], mat-dialog-content',
-  host: {
-    role: 'main'
-  }
+  selector: '[md-dialog-content], md-dialog-content, [mat-dialog-content], mat-dialog-content'
 })
 export class MdDialogContent { }
 

src/lib/dialog/dialog.spec.ts

@@ -343,16 +343,6 @@ describe('MdDialog', () => {
       expect(button.getAttribute('aria-label')).toBe('Best close button ever');
     });
 
-    it('should add a role to the dialog title', () => {
-      let header = overlayContainerElement.querySelector('[md-dialog-title]');
-      expect(header.getAttribute('role')).toBe('heading');
-    });
-
-    it('should add a role to the dialog content', () => {
-      let content = overlayContainerElement.querySelector('md-dialog-content');
-      expect(content.getAttribute('role')).toBe('main');
-    });
-
   });
 });