Update Canvas.js

CanvasApp/Canvas.js

@@ -834,8 +834,6 @@ function newCanvas () {
 
   function onMouseWheel (event) {
     try {
-      if (IS_MAC) { event.delta = event.delta / MAC_AMOUNT_FACTOR }
-
       thisObject.mouse.event = event
       thisObject.mouse.position.x = event.pageX
       thisObject.mouse.position.y = event.pageY - CURRENT_TOP_MARGIN
@@ -844,6 +842,7 @@ function newCanvas () {
            // cross-browser wheel delta
       var event = window.event || event // old IE support
       event.delta = Math.max(-1, Math.min(1, event.wheelDelta || -event.detail))
+      if (IS_MAC) { event.delta = event.delta / MAC_AMOUNT_FACTOR }
 
            /* We try first with panels. */