add small code tweaks

js/keyboard_input_manager.js

@@ -59,20 +59,22 @@ KeyboardInputManager.prototype.listen = function () {
   // Listen to swipe events
   var touchStartClientX, touchStartClientY;
   var gameContainer = document.getElementsByClassName("game-container")[0];
-  gameContainer.addEventListener("touchstart", function(event) {
+
+  gameContainer.addEventListener("touchstart", function (event) {
     if (event.touches.length > 1) return;
 
     touchStartClientX = event.touches[0].clientX;
     touchStartClientY = event.touches[0].clientY;
     event.preventDefault();
   });
-  gameContainer.addEventListener("touchmove", function(event) {
+
+  gameContainer.addEventListener("touchmove", function (event) {
     event.preventDefault();
   });
-  gameContainer.addEventListener("touchend", function(event) {
-    if (event.touches.length > 0) {
-      return;
-    }
+
+  gameContainer.addEventListener("touchend", function (event) {
+    if (event.touches.length > 0) return;
+
     var dx = event.changedTouches[0].clientX - touchStartClientX;
     var absDx = Math.abs(dx);