refactor(ngModel): move model -> view update from watchFn to watchAction

Author: Narretz

src/ng/directive/ngModel.js

@@ -731,6 +731,11 @@ var NgModelController = ['$scope', '$exceptionHandler', '$attrs', '$element', '$
         $exceptionHandler(e);
       }
     });
+    if (ctrl.$viewChangeListeners.length > 0 ||
+        ctrl.$options && ctrl.$options.getterSetter === true
+    ) {
+      modelToViewAction(ngModelGet($scope));
+    }
   };
 
   /**
@@ -820,19 +825,13 @@ var NgModelController = ['$scope', '$exceptionHandler', '$attrs', '$element', '$
     }
   };
 
-  // model -> value
-  // Note: we cannot use a normal scope.$watch as we want to detect the following:
-  // 1. scope value is 'a'
-  // 2. user enters 'b'
-  // 3. ng-change kicks in and reverts scope value to 'a'
-  //    -> scope value did not change since the last digest as
-  //       ng-change executes in apply phase
-  // 4. view should be changed back to 'a'
+  // model -> view
   $scope.$watch(function ngModelWatch() {
-    var modelValue = ngModelGet($scope);
+    return ngModelGet($scope);
+  }, ngModelWatchAction, ctrl.$options && ctrl.$options.deepWatch);
 
+  function ngModelWatchAction(modelValue) {
     // if scope model value and ngModel value are out of sync
-    // TODO(perf): why not move this to the action fn?
     if (modelValue !== ctrl.$modelValue &&
        // checks for NaN is needed to allow setting the model to NaN when there's an asyncValidator
        (ctrl.$modelValue === ctrl.$modelValue || modelValue === modelValue)
@@ -855,9 +854,7 @@ var NgModelController = ['$scope', '$exceptionHandler', '$attrs', '$element', '$
         ctrl.$$runValidators(modelValue, viewValue, noop);
       }
     }
-
-    return modelValue;
-  });
+  }
 }];