[Fixes #4853] use Object.create(null) directly (#4854)

addon/-private/system/clone-null.js

@@ -1,6 +1,5 @@
-import EmptyObject from "./empty-object";
 export default function cloneNull(source) {
-  let clone = new EmptyObject();
+  let clone = Object.create(null);
   for (let key in source) {
     clone[key] = source[key];
   }

addon/-private/system/model/internal-model.js

@@ -3,7 +3,6 @@ import { assert, runInDebug } from "ember-data/-private/debug";
 import RootState from "./states";
 import Relationships from "../relationships/state/create";
 import Snapshot from "../snapshot";
-import EmptyObject from "../empty-object";
 import isEnabled from '../../features';
 import OrderedSet from "../ordered-set";
 
@@ -42,10 +41,10 @@ const assign = Ember.assign || Ember.merge;
    and setups. It may also be faster to do a two level cache (from: { to }) instead of caching based
    on a key that adds the two together.
  */
-const TransitionChainMap = new EmptyObject();
+const TransitionChainMap = Object.create(null);
 
-const _extractPivotNameCache = new EmptyObject();
-const _splitOnDotCache = new EmptyObject();
+const _extractPivotNameCache = Object.create(null);
+const _splitOnDotCache = Object.create(null);
 
 function splitOnDot(name) {
   return _splitOnDotCache[name] || (
@@ -180,7 +179,7 @@ export default class InternalModel {
 
   get references() {
     if (this._references === null) {
-      this._references = new EmptyObject();
+      this._references = Object.create(null);
     }
     return this._references;
   }
@@ -194,7 +193,7 @@ export default class InternalModel {
 
   get _attributes() {
     if (this.__attributes === null) {
-      this.__attributes = new EmptyObject();
+      this.__attributes = Object.create(null);
     }
     return this.__attributes;
   }
@@ -213,7 +212,7 @@ export default class InternalModel {
 
   get _inFlightAttributes() {
     if (this.__inFlightAttributes === null) {
-      this.__inFlightAttributes = new EmptyObject();
+      this.__inFlightAttributes = Object.create(null);
     }
     return this.__inFlightAttributes;
   }
@@ -224,7 +223,7 @@ export default class InternalModel {
 
   get _data() {
     if (this.__data === null) {
-      this.__data = new EmptyObject();
+      this.__data = Object.create(null);
     }
     return this.__data;
   }
@@ -262,7 +261,7 @@ export default class InternalModel {
   */
   get _implicitRelationships() {
     if (this.__implicitRelationships === null) {
-      this.__implicitRelationships = new EmptyObject();
+      this.__implicitRelationships = Object.create(null);
     }
     return this.__implicitRelationships;
   }
@@ -598,7 +597,7 @@ export default class InternalModel {
   flushChangedAttributes() {
     heimdall.increment(flushChangedAttributes);
     this._inFlightAttributes = this._attributes;
-    this._attributes = new EmptyObject();
+    this._attributes = Object.create(null);
   }
 
   hasChangedAttributes() {
@@ -647,7 +646,7 @@ export default class InternalModel {
     let currentData = this._attributes;
     let inFlightData = this._inFlightAttributes;
     let newData = assign(copy(inFlightData), currentData);
-    let diffData = new EmptyObject();
+    let diffData = Object.create(null);
     let newDataKeys = Object.keys(newData);
 
     for (let i = 0, length = newDataKeys.length; i < length; i++) {
@@ -719,10 +718,10 @@ export default class InternalModel {
   rollbackAttributes() {
     let dirtyKeys = Object.keys(this._attributes);
 
-    this._attributes = new EmptyObject();
+    this._attributes = Object.create(null);
 
     if (get(this, 'isError')) {
-      this._inFlightAttributes = new EmptyObject();
+      this._inFlightAttributes = Object.create(null);
       this.didCleanError();
     }
 
@@ -739,7 +738,7 @@ export default class InternalModel {
     }
 
     if (this.isValid()) {
-      this._inFlightAttributes = new EmptyObject();
+      this._inFlightAttributes = Object.create(null);
     }
 
     this.send('rolledBack');
@@ -1005,7 +1004,7 @@ export default class InternalModel {
       assign(this._data, data);
     }
 
-    this._inFlightAttributes = new EmptyObject();
+    this._inFlightAttributes = Object.create(null);
 
     this.send('didCommit');
     this.updateRecordArrays();
@@ -1071,7 +1070,7 @@ export default class InternalModel {
         attrs[keys[i]] = this._inFlightAttributes[keys[i]];
       }
     }
-    this._inFlightAttributes = new EmptyObject();
+    this._inFlightAttributes = Object.create(null);
   }
 
   /*
@@ -1124,7 +1123,7 @@ export default class InternalModel {
       let length = keys.length;
       let attrs = this._attributes;
 
-      original = assign(new EmptyObject(), this._data);
+      original = assign(Object.create(null), this._data);
       original = assign(original, this._inFlightAttributes);
 
       for (i = 0; i < length; i++) {

addon/-private/system/model/model.js

@@ -4,7 +4,6 @@ import { PromiseObject } from "../promise-proxies";
 import Errors from "../model/errors";
 import isEnabled from '../../features';
 import RootState from '../model/states';
-import EmptyObject from "../empty-object";
 import {
   relationshipsByNameDescriptor,
   relatedTypesDescriptor,
@@ -1275,7 +1274,7 @@ Model.reopenClass({
   },
 
   inverseMap: Ember.computed(function() {
-    return new EmptyObject();
+    return Object.create(null);
   }),
 
   /**

addon/-private/system/relationships/state/create.js

@@ -1,7 +1,6 @@
 import Ember from 'ember';
 import ManyRelationship from "./has-many";
 import BelongsToRelationship from "./belongs-to";
-import EmptyObject from "../../empty-object";
 import { runInDebug } from 'ember-data/-private/debug';
 
 const { get } = Ember;
@@ -37,7 +36,7 @@ function createRelationshipFor(internalModel, relationshipMeta, store) {
 export default class Relationships {
   constructor(internalModel) {
     this.internalModel = internalModel;
-    this.initializedRelationships = new EmptyObject();
+    this.initializedRelationships = Object.create(null);
   }
 
   // TODO @runspired deprecate this as it was never truly a record instance

addon/-private/system/snapshot.js

@@ -3,7 +3,6 @@
 */
 
 import Ember from 'ember';
-import EmptyObject from "./empty-object";
 
 const {
   get
@@ -18,11 +17,11 @@ const {
 */
 export default class Snapshot {
   constructor(internalModel, options = {}) {
-    this._attributes = new EmptyObject();
-    this._belongsToRelationships = new EmptyObject();
-    this._belongsToIds = new EmptyObject();
-    this._hasManyRelationships = new EmptyObject();
-    this._hasManyIds = new EmptyObject();
+    this._attributes = Object.create(null);
+    this._belongsToRelationships = Object.create(null);
+    this._belongsToIds = Object.create(null);
+    this._hasManyRelationships = Object.create(null);
+    this._hasManyIds = Object.create(null);
     this._internalModel = internalModel;
 
     let record = internalModel.getRecord();
@@ -144,7 +143,7 @@ export default class Snapshot {
    @return {Object} All changed attributes of the current snapshot
    */
   changedAttributes() {
-    let changedAttributes = new EmptyObject();
+    let changedAttributes = Object.create(null);
     let changedAttributeKeys = Object.keys(this._changedAttributes);
 
     for (let i=0, length = changedAttributeKeys.length; i < length; i++) {

addon/-private/system/store.js

@@ -44,7 +44,6 @@ import coerceId from "./coerce-id";
 import RecordArrayManager from "./record-array-manager";
 import ContainerInstanceCache from './store/container-instance-cache';
 import InternalModel from "./model/internal-model";
-import EmptyObject from "./empty-object";
 import isEnabled from '../features';
 
 export let badIdFormatAssertion = '`id` passed to `findRecord()` has to be non-empty string or number';
@@ -219,7 +218,7 @@ Store = Service.extend({
     this._identityMap = new IdentityMap();
     this._pendingSave = [];
     this._instanceCache = new ContainerInstanceCache(getOwner(this), this);
-    this._modelFactoryCache = new EmptyObject();
+    this._modelFactoryCache = Object.create(null);
 
     /*
       Ember Data uses several specialized micro-queues for organizing
@@ -349,7 +348,7 @@ Store = Service.extend({
     assert(`You need to pass a model name to the store's createRecord method`, isPresent(modelName));
     assert(`Passing classes to store methods has been removed. Please pass a dasherized string instead of ${modelName}`, typeof modelName === 'string');
     let normalizedModelName = normalizeModelName(modelName);
-    let properties = copy(inputProperties) || new EmptyObject();
+    let properties = copy(inputProperties) || Object.create(null);
 
     // If the passed properties do not include a primary key,
     // give the adapter an opportunity to generate one. Typically,
@@ -860,7 +859,7 @@ Store = Service.extend({
     let shouldCoalesce = !!adapter.findMany && adapter.coalesceFindRequests;
     let totalItems = pendingFetchItems.length;
     let internalModels = new Array(totalItems);
-    let seeking = new EmptyObject();
+    let seeking = Object.create(null);
 
     for (let i = 0; i < totalItems; i++) {
       let pendingItem = pendingFetchItems[i];
@@ -880,7 +879,7 @@ Store = Service.extend({
 
     function handleFoundRecords(foundInternalModels, expectedInternalModels) {
       // resolve found records
-      let found = new EmptyObject();
+      let found = Object.create(null);
       for (let i = 0, l = foundInternalModels.length; i < l; i++) {
         let internalModel = foundInternalModels[i];
         let pair = seeking[internalModel.id];

addon/-private/system/store/container-instance-cache.js

@@ -1,6 +1,5 @@
 /* global heimdall */
 import Ember from 'ember';
-import EmptyObject from "../empty-object";
 const { set } = Ember;
 
 const  {
@@ -37,8 +36,8 @@ export default class ContainerInstanceCache {
     this._owner = owner;
     this._store = store;
     this._namespaces = {
-      adapter: new EmptyObject(),
-      serializer: new EmptyObject()
+      adapter: Object.create(null),
+      serializer: Object.create(null)
     };
   }
 

addon/-private/utils/parse-response-headers.js

@@ -1,9 +1,7 @@
-import EmptyObject from '../system/empty-object';
-
 const CLRF = '\u000d\u000a';
 
 export default function parseResponseHeaders(headersString) {
-  let headers = new EmptyObject();
+  let headers = Object.create(null);
 
   if (!headersString) {
     return headers;

tests/unit/utils/parse-response-headers-test.js

@@ -1,4 +1,3 @@
-import EmptyObject from 'ember-data/-private/system/empty-object';
 import parseResponseHeaders from 'ember-data/-private/utils/parse-response-headers';
 import { module, test } from 'qunit';
 
@@ -9,7 +8,7 @@ module('unit/adapters/parse-response-headers');
 test('returns an EmptyObject when headersString is undefined', function(assert) {
   let headers = parseResponseHeaders(undefined);
 
-  assert.deepEqual(headers, new EmptyObject(), 'EmptyObject is returned');
+  assert.deepEqual(headers, Object.create(null), 'EmptyObject is returned');
 });
 
 test('header parsing', function(assert) {