fix broken test

Author: mmalerba

src/material-experimental/mdc-list/list.spec.ts

@@ -1,3 +1,6 @@
+import {MatList} from '@angular/material-experimental/mdc-list';
+
 it('should have unit tests', () => {
   // TODO: Implement.
+  expect(MatList).toBe(MatList);
 });

src/material-experimental/mdc-list/nav-list.ts

@@ -7,7 +7,7 @@
  */
 
 import {ChangeDetectionStrategy, Component, ViewEncapsulation} from '@angular/core';
-import {MatList} from '@angular/material-experimental/mdc-list/list';
+import {MatList} from './list';
 import {MatListBase} from './list-base';
 
 @Component({