fix(slider): role was applied to inner element instead of the directive itself (#10731)

fixes #10565

Author: EladBezalel

src/components/slider/slider.js

@@ -172,7 +172,7 @@ function SliderDirective($$rAF, $window, $mdAria, $mdUtil, $mdConstant, $mdThemi
 
     if (tAttrs.disabled || tAttrs.ngDisabled) wrapper.attr('tabindex', -1);
 
-    wrapper.attr('role', 'slider');
+    tElement.attr('role', 'slider');
 
     $mdAria.expect(tElement, 'aria-label');
 

src/components/slider/slider.spec.js

@@ -190,7 +190,7 @@ describe('md-slider', function() {
 
     pageScope.$apply('model = 102');
 
-    expect(wrapper.attr('role')).toEqual('slider');
+    expect(slider.attr('role')).toEqual('slider');
     expect(slider.attr('aria-valuemin')).toEqual('100');
     expect(slider.attr('aria-valuemax')).toEqual('104');
     expect(slider.attr('aria-valuenow')).toEqual('102');