feat(noConflict): restore previous namespace

src/Angular.js

@@ -58,12 +58,33 @@ var Error             = window.Error,
     push              = [].push,
     toString          = Object.prototype.toString,
 
+
+    _angular          = window.angular, 
     /** @name angular */
-    angular           = window.angular || (window.angular = {}),
+    angular           = window.angular = {},
     angularModule,
     nodeName_,
     uid               = ['0', '0', '0'];
 
+/**
+ * @ngdoc function
+ * @name angular.noConflict
+ * @function
+ *
+ * @description
+ * Restores the previous global value of angular and returns the current instance. Other libraries 
+ * may already use the angular namespace. Or a previous version of angular is already loaded on 
+ * the page. In these cases you may want to restore the previous namespace and keep a reference to 
+ * angular. 
+ *
+ * @returns {Object} the current angular namespace
+ */
+function noConflict() {
+  var a = window.angular;
+  window.angular = _angular;
+  return a;
+}
+
 /**
  * @ngdoc function
  * @name angular.forEach

src/AngularPublic.js

@@ -48,7 +48,8 @@ function publishExternalAPI(angular){
     'isDate': isDate,
     'lowercase': lowercase,
     'uppercase': uppercase,
-    'callbacks': {counter: 0}
+    'callbacks': {counter: 0},
+    'noConflict': noConflict
   });
 
   angularModule = setupModuleLoader(window);

test/AngularSpec.js

@@ -632,4 +632,27 @@ describe('angular', function() {
       expect(toJson({key: $rootScope})).toEqual('{"key":"$SCOPE"}');
     }));
   });
+
+  describe('noConflict', function() {
+    var globalAngular;
+    beforeEach(function() {
+      globalAngular = angular;  
+    });
+
+    afterEach(function() {
+      angular = globalAngular;  
+    });
+
+    it('should return angular', function() {
+      var a = angular.noConflict();
+      expect(a).toBe(globalAngular);
+    });
+
+    it('should restore original angular', function() {
+      var a = angular.noConflict();
+      expect(angular).toBeUndefined();
+    });
+
+  });
+
 });