fix(slider): run all tests Closes #6794

Author: Aleksandyr

projects/igniteui-angular/src/lib/slider/slider.component.spec.ts

@@ -28,7 +28,7 @@ interface FakeDoc {
     documentElement: { dir?: string };
 }
 
-fdescribe('IgxSlider', () => {
+describe('IgxSlider', () => {
     let fakeDoc: FakeDoc;
     configureTestSuite();
     beforeAll(async(() => {