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

src/Angular.js

@@ -263,7 +263,7 @@ 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/input.js

@@ -1744,8 +1744,8 @@ 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/inputSpec.js

@@ -50,6 +50,22 @@ describe('NgModelController', 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() {