perf($animate): access DOM less in resolveElementClasses

Previously we were reading DOM attributes frequently, now we can do it just once.

Author: caitp

src/ng/animate.js

@@ -102,8 +102,14 @@ var $AnimateProvider = ['$provide', function($provide) {
 
     function resolveElementClasses(element, cache) {
       var toAdd = [], toRemove = [];
+
+      var hasClasses = createMap();
+      forEach((element.attr('class') || '').split(/\s+/), function(className) {
+        hasClasses[className] = true;
+      });
+
       forEach(cache.classes, function(status, className) {
-        var hasClass = jqLiteHasClass(element[0], className);
+        var hasClass = hasClasses[className];
 
         // If the most recent class manipulation (via $animate) was to remove the class, and the
         // element currently has the class, the class is scheduled for removal. Otherwise, if

src/ngAnimate/animate.js

@@ -477,9 +477,14 @@ angular.module('ngAnimate', ['ng'])
           });
         });
 
+        var hasClasses = Object.create(null);
+        forEach((element.attr('class') || '').split(/\s+/), function(className) {
+          hasClasses[className] = true;
+        });
+
         var toAdd = [], toRemove = [];
         forEach(cache.classes, function(status, className) {
-          var hasClass = angular.$$hasClass(element[0], className);
+          var hasClass = hasClasses[className] === true;
           var matchingAnimation = lookup[className] || {};
 
           // When addClass and removeClass is called then $animate will check to