Minor beautification.

src/core/EventDispatcher.js

@@ -77,9 +77,10 @@ THREE.EventDispatcher.prototype = {
 
 		if ( listenerArray !== undefined ) {
 
-			listenerArray = listenerArray.slice();
 			event.target = this;
 
+			listenerArray = listenerArray.slice();
+
 			for ( var i = 0, l = listenerArray.length; i < l; i ++ ) {
 
 				listenerArray[ i ].call( this, event );