Util shouldn't modify window object

This commits prevents Util from modifying the window object.

- `window.requestAnimFrame` was removed (no polyfill is needed anymore)
- the potential redefinition of `console.log` and friends was removed
  (all supported browsers have `console.xyz` defined anyway)

core/display.js

@@ -778,7 +778,7 @@
             }
 
             if (this._renderQ.length > 0) {
-                requestAnimFrame(this._scan_renderQ.bind(this));
+                requestAnimationFrame(this._scan_renderQ.bind(this));
             }
         },
     };