minimize triggerEvent code path when no listeners, r=tschaub (closes #2014)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@9142 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Events.js

@@ -693,6 +693,12 @@ OpenLayers.Events = OpenLayers.Class({
      *     chain of listeners will stop getting called.
      */
     triggerEvent: function (type, evt) {
+        var listeners = this.listeners[type];
+
+        // fast path
+        if(!listeners || listeners.length == 0) {
+            return;
+        }
 
         // prep evt object with object & div references
         if (evt == null) {
@@ -707,10 +713,7 @@ OpenLayers.Events = OpenLayers.Class({
         // execute all callbacks registered for specified type
         // get a clone of the listeners array to
         // allow for splicing during callbacks
-        var listeners = (this.listeners[type]) ?
+        var listeners = listeners.slice(), continueChain;
-                            this.listeners[type].slice() : null;
-        if ((listeners != null) && (listeners.length > 0)) {
-            var continueChain;
         for (var i=0, len=listeners.length; i<len; i++) {
             var callback = listeners[i];
             // bind the context to callback.obj
@@ -725,7 +728,6 @@ OpenLayers.Events = OpenLayers.Class({
         if (!this.fallThrough) {           
             OpenLayers.Event.stop(evt, true);
         }
-        }
         return continueChain;
     },