Add KeyboardEvent constructor polyfill

(cherry picked from commit 11ae2ff43f)

src/index.jsx

@@ -32,6 +32,7 @@ import './components/playback/playerSelectionMenu';
 import './legacy/domParserTextHtml';
 import './legacy/focusPreventScroll';
 import './legacy/htmlMediaElement';
+import './legacy/keyboardEvent';
 import './legacy/vendorStyles';
 import { currentSettings } from './scripts/settings/userSettings';
 import taskButton from './scripts/taskbutton';

src/legacy/keyboardEvent.js

@@ -0,0 +1,48 @@
+/**
+ * Polyfill for KeyboardEvent
+ * - Constructor.
+ */
+
+(function (window) {
+    'use strict';
+
+    try {
+        new window.KeyboardEvent('event', { bubbles: true, cancelable: true });
+    } catch (e) {
+        // We can't use `KeyboardEvent` in old WebKit because `initKeyboardEvent`
+        // doesn't seem to populate some properties (`keyCode`, `which`) that
+        // are read-only.
+        const KeyboardEventOriginal = window.Event;
+
+        const KeyboardEvent = function (eventName, options) {
+            options = options || {};
+
+            const event = document.createEvent('Event');
+
+            event.initEvent(eventName, !!options.bubbles, !!options.cancelable);
+
+            event.view = options.view || document.defaultView;
+
+            event.key = options.key || options.keyIdentifier || '';
+            event.keyCode = options.keyCode || 0;
+            event.code = options.code || '';
+            event.charCode = options.charCode || 0;
+            event.char = options.char || '';
+            event.which = options.which || 0;
+
+            event.location = options.location || options.keyLocation || 0;
+
+            event.ctrlKey = !!options.ctrlKey;
+            event.altKey = !!options.altKey;
+            event.shiftKey = !!options.shiftKey;
+            event.metaKey = !!options.metaKey;
+
+            event.repeat = !!options.repeat;
+
+            return event;
+        };
+
+        KeyboardEvent.prototype = KeyboardEventOriginal.prototype;
+        window.KeyboardEvent = KeyboardEvent;
+    }
+}(window));