Don't bother parsing integer because already integer

https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/offsetWidth

If offsetWidth is defined, it will already be an integer.
If offsetWidth is not defined, ig.system.realWidth will be used instead.

lib/impact/input.js

@@ -171,7 +171,7 @@ ig.Input = ig.Class.extend({
 
 
 	mousemove: function( event ) {		
-		var internalWidth = parseInt(ig.system.canvas.offsetWidth) || ig.system.realWidth;
+		var internalWidth = ig.system.canvas.offsetWidth || ig.system.realWidth;
 		var scale = ig.system.scale * (internalWidth / ig.system.realWidth);
 
 		var pos = {left: 0, top: 0};