fix(tabs): dummy tabs should not have acccessibilty roles (#9452)

* Remove role="tab" from dummy tabs

Fixes #9450

Author: clshortfuse

src/components/tabs/js/tabsDirective.js

@@ -169,7 +169,6 @@ function MdTabs ($$mdSvgRegistry) {
                   'class="md-tab" ' +
                   'tabindex="-1" ' +
                   'id="tab-item-{{::tab.id}}" ' +
-                  'role="tab" ' +
                   'aria-controls="tab-content-{{::tab.id}}" ' +
                   'aria-selected="{{tab.isActive()}}" ' +
                   'aria-disabled="{{tab.scope.disabled || \'false\'}}" ' +

src/components/tabs/tabs.spec.js

@@ -354,7 +354,6 @@ describe('<md-tabs>', function () {
       expect(tabs.find('md-tabs-canvas').attr('role')).toBe('tablist');
 
       expect(tabItem.attr('id')).toBeTruthy();
-      expect(tabItem.attr('role')).toBe('tab');
       expect(tabItem.attr('aria-controls')).toBe(tabContent.attr('id'));
 
       expect(tabContent.attr('id')).toBeTruthy();
@@ -364,6 +363,24 @@ describe('<md-tabs>', function () {
       //Unique ids check
       expect(tabContent.attr('id')).not.toEqual(tabItem.attr('id'));
     });
+
+    it('should not assign role to dummy tabs', function () {
+      var tabs       = setup('<md-tabs>' +
+                             '<md-tab label="label!">content!</md-tab>' +
+                             '</md-tabs>');
+      var tabItem    = tabs.find('md-dummy-tab');
+
+      expect(tabItem.attr('role')).toBeFalsy();
+    });
+
+    it('should assign role to visible tabs', function () {
+      var tabs       = setup('<md-tabs>' +
+                             '<md-tab label="label!">content!</md-tab>' +
+                             '</md-tabs>');
+      var tabItem    = tabs.find('md-tab-item');
+
+      expect(tabItem.attr('role')).toBe('tab');
+    });
   });
 
   describe('<md-tab>', function () {