refactor(combobox): removed commented out import and fixed the name of an input reference in the combobox spec.

Author: nielsr98

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

@@ -77,7 +77,7 @@ describe('Combobox', () => {
   template: `
   <button cdkCombobox #toggleCombobox class="example-combobox"
           [cdkComboboxTriggerFor]="panel"
-          [openAction]="'focus'">
+          [openActions]="'focus'">
     No Value
   </button>
 

src/dev-app/cdk-experimental-combobox/cdk-combobox-demo-module.ts

@@ -10,7 +10,6 @@ import {NgModule} from '@angular/core';
 import {CommonModule} from '@angular/common';
 import {RouterModule} from '@angular/router';
 import {CdkComboboxModule} from '@angular/cdk-experimental/combobox';
-// import {FormsModule, ReactiveFormsModule} from '@angular/forms';
 import {CdkComboboxDemo} from './cdk-combobox-demo';
 import {PanelContent} from './panel-content';