[BUGFIX] fix importing from @ember-data/store

Dividing Record Data into packages (#6513) configured the Store class
inside of the `-ember-data` metapackage. This broke importing the Store directly from `@ember-data/store`,
which this commit fixes.

packages/-ember-data/addon/store.ts

@@ -1,21 +1 @@
-import { IDENTIFIERS } from '@ember-data/canary-features';
-import { RecordData } from '@ember-data/record-data/-private';
-import Store from '@ember-data/store';
-import { identifierCacheFor } from '@ember-data/store/-private';
-
-type RecordDataStoreWrapper = import('@ember-data/store/-private/ts-interfaces/record-data-store-wrapper').RecordDataStoreWrapper;
-
-export default class DefaultStore extends Store {
-  createRecordDataFor(modelName: string, id: string | null, clientId: string, storeWrapper: RecordDataStoreWrapper) {
-    if (IDENTIFIERS) {
-      let identifier = identifierCacheFor(this).getOrCreateRecordIdentifier({
-        type: modelName,
-        id,
-        lid: clientId,
-      });
-      return new RecordData(identifier, storeWrapper);
-    } else {
-      return new RecordData(modelName, id, clientId, storeWrapper);
-    }
-  }
-}
+export { default } from '@ember-data/store';

packages/-ember-data/tests/integration/store/package-import-test.js

@@ -0,0 +1,70 @@
+import { get } from '@ember/object';
+import { settled } from '@ember/test-helpers';
+
+import { module, test } from 'qunit';
+
+import { setupTest } from 'ember-qunit';
+
+import Model, { attr } from '@ember-data/model';
+import Store from '@ember-data/store';
+
+class Person extends Model {
+  @attr()
+  name;
+}
+
+class CustomStore extends Store {}
+
+module('integration/store/package-import', function(hooks) {
+  setupTest(hooks);
+
+  let store;
+
+  hooks.beforeEach(function() {
+    let { owner } = this;
+
+    owner.register('model:person', Person);
+    owner.unregister('service:store');
+    owner.register('service:store', CustomStore);
+    store = owner.lookup('service:store');
+  });
+
+  test('Store push works with an import from @ember-data/store', async function(assert) {
+    store.push({
+      data: [
+        {
+          type: 'person',
+          id: '1',
+          attributes: {
+            name: 'Scumbag Dale',
+          },
+        },
+        {
+          type: 'person',
+          id: '2',
+          attributes: {
+            name: 'Scumbag Katz',
+          },
+        },
+      ],
+    });
+
+    let all = store.peekAll('person');
+    assert.equal(get(all, 'length'), 2);
+
+    store.push({
+      data: [
+        {
+          type: 'person',
+          id: '3',
+          attributes: {
+            name: 'Scumbag Bryn',
+          },
+        },
+      ],
+    });
+
+    await settled();
+    assert.equal(get(all, 'length'), 3);
+  });
+});

packages/store/addon/-private/system/ds-model-store.ts

@@ -10,14 +10,20 @@ import { assign } from '@ember/polyfills';
 import { isPresent } from '@ember/utils';
 import { DEBUG } from '@glimmer/env';
 
-import { CUSTOM_MODEL_CLASS } from '@ember-data/canary-features';
+import { CUSTOM_MODEL_CLASS, IDENTIFIERS } from '@ember-data/canary-features';
+import { HAS_RECORD_DATA_PACKAGE } from '@ember-data/private-build-infra';
 
+import { identifierCacheFor } from '../identifiers/cache';
 import CoreStore from './core-store';
 import notifyChanges from './model/notify-changes';
 import { getShimClass } from './model/shim-model-class';
 import normalizeModelName from './normalize-model-name';
 import { DSModelSchemaDefinitionService, getModelFactory } from './schema-definition-service';
 
+type RecordDataStoreWrapper = import('./store/record-data-store-wrapper').default;
+
+const RecordData = HAS_RECORD_DATA_PACKAGE ? require('@ember-data/record-data/-private').RecordData : null;
+
 type RelationshipsSchema = import('../ts-interfaces/record-data-schemas').RelationshipsSchema;
 type SchemaDefinitionService = import('../ts-interfaces/schema-definition-service').SchemaDefinitionService;
 type RecordDataRecordWrapper = import('../ts-interfaces/record-data-record-wrapper').RecordDataRecordWrapper;
@@ -136,14 +142,31 @@ class Store extends CoreStore {
     record.destroy();
   }
 
+  createRecordDataFor(modelName: string, id: string | null, clientId: string, storeWrapper: RecordDataStoreWrapper) {
+    if (HAS_RECORD_DATA_PACKAGE) {
+      if (IDENTIFIERS) {
+        let identifier = identifierCacheFor(this).getOrCreateRecordIdentifier({
+          type: modelName,
+          id,
+          lid: clientId,
+        });
+        return new RecordData(identifier, storeWrapper);
+      } else {
+        return new RecordData(modelName, id, clientId, storeWrapper);
+      }
+    } else {
+      throw new Error(`Expected store.createRecordDataFor to be implemented but it wasn't`);
+    }
+  }
+
   /**
   Returns the model class for the particular `modelName`.
-
+ 
   The class of a model might be useful if you want to get a list of all the
   relationship names of the model, see
   [`relationshipNames`](/ember-data/release/classes/Model?anchor=relationshipNames)
   for example.
-
+ 
   @method modelFor
   @param {String} modelName
   @return {Model}
@@ -192,10 +215,10 @@ class Store extends CoreStore {
   This exists for legacy support for the RESTSerializer,
   which due to how it must guess whether a key is a model
   must query for whether a match exists.
-
+ 
   We should investigate an RFC to make this public or removing
   this requirement.
-
+ 
   @private
  */
   _hasModelFor(modelName) {