fix(form): ignore properties in $error prototype chain

Closes #10469
Closes #10727

Author: caitp

src/Angular.js

@@ -262,7 +262,7 @@ function forEach(obj, iterator, context) {
         obj.forEach(iterator, context, obj);
     } else {
       for (key in obj) {
-        if (obj.hasOwnProperty(key)) {
+        if (hasOwnProperty.call(obj, key)) {
           iterator.call(context, obj[key], key, obj);
         }
       }

src/ng/directive/form.js

@@ -67,8 +67,8 @@ function FormController(element, attrs, $scope, $animate, $interpolate) {
   var parentForm = form.$$parentForm = element.parent().controller('form') || nullFormCtrl;
 
   // init state
-  form.$error = {};
-  form.$$success = {};
+  form.$error = createMap();
+  form.$$success = createMap();
   form.$pending = undefined;
   form.$name = $interpolate(attrs.name || attrs.ngForm || '')($scope);
   form.$dirty = false;

src/ng/directive/ngModel.js

@@ -233,8 +233,8 @@ var NgModelController = ['$scope', '$exceptionHandler', '$attrs', '$element', '$
   this.$dirty = false;
   this.$valid = true;
   this.$invalid = false;
-  this.$error = {}; // keep invalid keys here
-  this.$$success = {}; // keep valid keys here
+  this.$error = createMap(); // keep invalid keys here
+  this.$$success = createMap(); // keep valid keys here
   this.$pending = undefined; // keep pending keys here
   this.$name = $interpolate($attr.name || '', false)($scope);
 

test/ng/directive/ngModelSpec.js

@@ -54,6 +54,22 @@ describe('ngModel', function() {
     });
 
 
+    it('should ignore items in prototype chain when determining validity', inject(function($compile) {
+      dealoc(element);
+      Object.prototype.someProp = true;
+      element = $compile('<form name="form"><input type="text" ng-model="value" name="value"></form>')(scope);
+      var input = element.children().eq(0);
+      ctrl = input.controller('ngModel');
+      var form = element.controller('form');
+      scope.$digest();
+      expect(ctrl.$valid).toBe(true);
+      expect(element.children()).toBeValid();
+      expect(form.$valid).toBe(true);
+      expect(element).toBeValid();
+      delete Object.prototype.someProp;
+    }));
+
+
     describe('setValidity', function() {
 
       function expectOneError() {