fix(nav-drawer): retain makrup classes, #6508

Author: wnvko

projects/igniteui-angular/src/lib/navigation-drawer/navigation-drawer.component.spec.ts

@@ -12,7 +12,7 @@ import { PlatformUtil } from '../core/utils';
 declare var Simulator: any;
 const oldTimeout = jasmine.DEFAULT_TIMEOUT_INTERVAL;
 
-fdescribe('Navigation Drawer', () => {
+describe('Navigation Drawer', () => {
     let widthSpyOverride: jasmine.Spy;
     // configureTestSuite();
     beforeEach(async(() => {

projects/igniteui-angular/src/lib/navigation-drawer/navigation-drawer.component.ts

@@ -61,8 +61,12 @@ export class IgxNavigationDrawerComponent implements
     AfterContentInit,
     OnDestroy,
     OnChanges {
+
     private _isOpen = false;
-    @HostBinding('class') public cssClass = 'igx-nav-drawer';
+
+    /** @hidden @internal */
+    @HostBinding('class.igx-nav-drawer')
+    public cssClass = true;
 
     /**
      * ID of the component