fix(selection-list): unable to select using the enter key (#8595)

Fixes not being able to select items in the selection list using enter.

Fixes #8589.

src/lib/list/selection-list.spec.ts

@@ -1,4 +1,4 @@
-import {DOWN_ARROW, SPACE, UP_ARROW} from '@angular/cdk/keycodes';
+import {DOWN_ARROW, SPACE, ENTER, UP_ARROW} from '@angular/cdk/keycodes';
 import {Platform} from '@angular/cdk/platform';
 import {createKeyboardEvent, dispatchFakeEvent} from '@angular/cdk/testing';
 import {Component, DebugElement} from '@angular/core';
@@ -188,10 +188,9 @@ describe('MatSelectionList without forms', () => {
     });
 
     it('should be able to use keyboard select with SPACE', () => {
-      let testListItem = listOptions[1].nativeElement as HTMLElement;
-      let SPACE_EVENT: KeyboardEvent =
-        createKeyboardEvent('keydown', SPACE, testListItem);
-      let selectList =
+      const testListItem = listOptions[1].nativeElement as HTMLElement;
+      const SPACE_EVENT: KeyboardEvent = createKeyboardEvent('keydown', SPACE, testListItem);
+      const selectList =
           selectionList.injector.get<MatSelectionList>(MatSelectionList).selectedOptions;
       expect(selectList.selected.length).toBe(0);
 
@@ -201,6 +200,23 @@ describe('MatSelectionList without forms', () => {
       fixture.detectChanges();
 
       expect(selectList.selected.length).toBe(1);
+      expect(SPACE_EVENT.defaultPrevented).toBe(true);
+    });
+
+    it('should be able to select an item using ENTER', () => {
+      const testListItem = listOptions[1].nativeElement as HTMLElement;
+      const ENTER_EVENT: KeyboardEvent = createKeyboardEvent('keydown', ENTER, testListItem);
+      const selectList =
+          selectionList.injector.get<MatSelectionList>(MatSelectionList).selectedOptions;
+      expect(selectList.selected.length).toBe(0);
+
+      dispatchFakeEvent(testListItem, 'focus');
+      selectionList.componentInstance._keydown(ENTER_EVENT);
+
+      fixture.detectChanges();
+
+      expect(selectList.selected.length).toBe(1);
+      expect(ENTER_EVENT.defaultPrevented).toBe(true);
     });
 
     it('should restore focus if active option is destroyed', () => {

src/lib/list/selection-list.ts

@@ -9,7 +9,7 @@
 import {FocusableOption, FocusKeyManager} from '@angular/cdk/a11y';
 import {coerceBooleanProperty} from '@angular/cdk/coercion';
 import {SelectionModel} from '@angular/cdk/collections';
-import {SPACE} from '@angular/cdk/keycodes';
+import {SPACE, ENTER} from '@angular/cdk/keycodes';
 import {
   AfterContentInit,
   Attribute,
@@ -343,6 +343,7 @@ export class MatSelectionList extends _MatSelectionListMixinBase implements Focu
   _keydown(event: KeyboardEvent) {
     switch (event.keyCode) {
       case SPACE:
+      case ENTER:
         this._toggleSelectOnFocusedOption();
         // Always prevent space from scrolling the page since the list has focus
         event.preventDefault();