docs(tutorial/step-4): controllers are no longer global functions

The docs did not line up with the codebase / previous steps of the tutorial.

Closes #4988

Author: chanced

docs/content/tutorial/step_04.ngdoc

@@ -112,11 +112,12 @@ describe('PhoneCat controllers', function() {
   describe('PhoneListCtrl', function(){
     var scope, ctrl;
 
-    beforeEach(function() {
-      scope = {},
-      ctrl = new PhoneListCtrl(scope);
-    });
-
+    beforeEach(module('phonecatApp'));
+    
+    beforeEach(inject(function($controller) {
+      scope = {};
+      ctrl = $controller('PhoneListCtrl', {$scope:scope});
+    }));
 
     it('should create "phones" model with 3 phones', function() {
       expect(scope.phones.length).toBe(3);