add OpenLayers.TRANSITION and OpenLayers.TRANSITION_END private constants

lib/OpenLayers/Util.js

@@ -1435,6 +1435,34 @@ OpenLayers.BROWSER_NAME = (function() {
     return name;
 })();
 
+(function() {
+    function testProp(props) {
+        var style = document.documentElement.style;
+        for (var i=0; i<props.length; i++) {
+            if(props[i] in style) {
+                return props[i];
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Constant: TRANSITION
+     */
+    OpenLayers.TRANSITION = testProp([
+        'transition', 'webkitTransition', 'MozTransition'
+    ]);
+
+    /**
+     * Constant: OpenLayers.TRANSITION_END
+     */
+    OpenLayers.TRANSITION_END = OpenLayers.TRANSITION === 'webkitTransition' ?
+        OpenLayers.TRANSITION + 'End' : 'transitionend';
+})();
+
+
+
+
 /**
  * Function: getBrowserName
  *