lint(combobox): removed trailing whitespace.

Author: nielsr98

src/cdk-experimental/combobox/combobox.spec.ts

@@ -80,7 +80,7 @@ describe('Combobox', () => {
           [openActions]="'focus'">
     No Value
   </button>
-  
+
   <ng-template cdkComboboxPanel #panel="cdkComboboxPanel">
     Panel Content
   </ng-template>`,