fix(a11y): don't handle disallowed modifier keys in typeahead mode (#14301)

Recently we switched to skip handling keyboard events with modifiers, unless the consumer opted into them explicitly. The changes weren't applied when in typeahead mode.

Fixes #14274.

Author: crisbeto

src/cdk/a11y/key-manager/list-key-manager.spec.ts

@@ -664,6 +664,30 @@ describe('Key managers', () => {
         expect(keyManager.activeItem).toBe(itemList.items[1]);
       }));
 
+      it('should not move focus if a modifier, that is not allowed, is pressed', fakeAsync(() => {
+        const tEvent = createKeyboardEvent('keydown', 84, undefined, 't');
+        Object.defineProperty(tEvent, 'ctrlKey', {get: () => true});
+
+        expect(keyManager.activeItem).toBeFalsy();
+
+        keyManager.onKeydown(tEvent); // types "t"
+        tick(debounceInterval);
+
+        expect(keyManager.activeItem).toBeFalsy();
+      }));
+
+      it('should always allow the shift key', fakeAsync(() => {
+        const tEvent = createKeyboardEvent('keydown', 84, undefined, 't');
+        Object.defineProperty(tEvent, 'shiftKey', {get: () => true});
+
+        expect(keyManager.activeItem).toBeFalsy();
+
+        keyManager.onKeydown(tEvent); // types "t"
+        tick(debounceInterval);
+
+        expect(keyManager.activeItem).toBeTruthy();
+      }));
+
       it('should focus the first item that starts with sequence of letters', fakeAsync(() => {
         keyManager.onKeydown(createKeyboardEvent('keydown', 84, undefined, 't')); // types "t"
         keyManager.onKeydown(createKeyboardEvent('keydown', 72, undefined, 'h')); // types "h"

src/cdk/a11y/key-manager/list-key-manager.ts

@@ -18,6 +18,7 @@ import {
   Z,
   ZERO,
   NINE,
+  hasModifierKey,
 } from '@angular/cdk/keycodes';
 import {debounceTime, filter, map, tap} from 'rxjs/operators';
 
@@ -244,12 +245,14 @@ export class ListKeyManager<T extends ListKeyManagerOption> {
         }
 
       default:
-        // Attempt to use the `event.key` which also maps it to the user's keyboard language,
-        // otherwise fall back to resolving alphanumeric characters via the keyCode.
-        if (event.key && event.key.length === 1) {
-          this._letterKeyStream.next(event.key.toLocaleUpperCase());
-        } else if ((keyCode >= A && keyCode <= Z) || (keyCode >= ZERO && keyCode <= NINE)) {
-          this._letterKeyStream.next(String.fromCharCode(keyCode));
+      if (isModifierAllowed || hasModifierKey(event, 'shiftKey')) {
+          // Attempt to use the `event.key` which also maps it to the user's keyboard language,
+          // otherwise fall back to resolving alphanumeric characters via the keyCode.
+          if (event.key && event.key.length === 1) {
+            this._letterKeyStream.next(event.key.toLocaleUpperCase());
+          } else if ((keyCode >= A && keyCode <= Z) || (keyCode >= ZERO && keyCode <= NINE)) {
+            this._letterKeyStream.next(String.fromCharCode(keyCode));
+          }
         }
 
         // Note that we return here, in order to avoid preventing