remove unused fields & unneeded vendor prefixes

main.js

@@ -97,19 +97,6 @@ class SnesInput {
 
 class InputHandler {
   constructor() {
-    this.up = false;
-    this.down = false;
-    this.left = false;
-    this.right = false;
-    this.a = false;
-    this.b = false;
-    this.x = false;
-    this.y = false;
-    this.l = false;
-    this.r = false;
-    this.select = false;
-    this.start = false;
-
     this.keysPressed = {};
 
     window.addEventListener('gamepadconnected', this.gamepadConnected);
@@ -183,9 +170,6 @@ class Graphics {
     this.canvas_ = canvas;
     this.ctx_ = canvas.getContext('2d');
     this.ctx_.imageSmoothingEnabled = false;
-    this.ctx_.mozImageSmoothingEnabled = false;
-    this.ctx_.webkitImageSmoothingEnabled = false;
-    this.ctx_.msImageSmoothingEnabled = false;
   }
 
   get width() {