support IE11

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

@@ -1,5 +1,6 @@
 import { A } from '@ember/array';
 import { set, get } from '@ember/object';
+import { assign } from '@ember/polyfills';
 import EmberError from '@ember/error';
 import { isEqual } from '@ember/utils';
 import { setOwner } from '@ember/application';
@@ -632,7 +633,7 @@ export default class InternalModel {
       changedKeys = this._changedKeys(data.attributes);
     }
 
-    Object.assign(this._data, data.attributes);
+    assign(this._data, data.attributes);
     this.pushedData();
 
     if (this.hasRecord) {
@@ -805,7 +806,7 @@ export default class InternalModel {
     let oldData = this._data;
     let currentData = this._attributes;
     let inFlightData = this._inFlightAttributes;
-    let newData = Object.assign({}, inFlightData, currentData);
+    let newData = assign({}, inFlightData, currentData);
     let diffData = Object.create(null);
     let newDataKeys = Object.keys(newData);
 
@@ -1169,9 +1170,9 @@ export default class InternalModel {
     this.didCleanError();
     let changedKeys = this._changedKeys(data);
 
-    Object.assign(this._data, this._inFlightAttributes);
+    assign(this._data, this._inFlightAttributes);
     if (data) {
-      Object.assign(this._data, data);
+      assign(this._data, data);
     }
 
     this._inFlightAttributes = null;
@@ -1300,7 +1301,7 @@ export default class InternalModel {
       }
 
       original = Object.create(null);
-      Object.assign(original, this._data, this._inFlightAttributes);
+      assign(original, this._data, this._inFlightAttributes);
 
       for (i = 0; i < length; i++) {
         key = keys[i];

addon/-private/system/snapshot.js

@@ -4,6 +4,7 @@
 import { inspect } from '@ember/debug';
 import EmberError from '@ember/error';
 import { get } from '@ember/object';
+import { assign } from '@ember/polyfills';
 
 /**
   @class Snapshot
@@ -147,7 +148,7 @@ export default class Snapshot {
    @return {Object} All attributes of the current snapshot
    */
   attributes() {
-    return Object.assign({}, this._attributes);
+    return assign({}, this._attributes);
   }
 
   /**

addon/-private/system/store.js

@@ -7,6 +7,7 @@ import EmberError from '@ember/error';
 import MapWithDefault from './map-with-default';
 import { run as emberRun } from '@ember/runloop';
 import { set, get, computed } from '@ember/object';
+import { assign } from '@ember/polyfills';
 import { default as RSVP, Promise } from 'rsvp';
 import Service from '@ember/service';
 import { typeOf, isPresent, isNone } from '@ember/utils';
@@ -319,7 +320,7 @@ Store = Service.extend({
     return emberRun.join(() => {
       return this._backburner.join(() => {
         let normalizedModelName = normalizeModelName(modelName);
-        let properties = Object.assign({}, inputProperties);
+        let properties = assign({}, inputProperties);
 
         // If the passed properties do not include a primary key,
         // give the adapter an opportunity to generate one. Typically,