convert classes to es6

(cherry picked from commit e7615d49a4071fe5b5f192884f142c9f3385211a)

src/js/net/minecraft/util/Keyboard.js

@@ -1,17 +1,14 @@
-window.Keyboard = class {
+export default class Keyboard {
 
     static state = {};
 
     static create() {
         window.addEventListener('keydown', function (event) {
-            //event.preventDefault();
             Keyboard.state[event.code] = true;
-            //console.log("Key " + event.code + " down");
         });
         window.addEventListener('keyup', function (event) {
             event.preventDefault();
             delete Keyboard.state[event.code];
-            //console.log("Key " + event.code + " up");
         });
     };