Issue #2609904 by timmillwood, dawehner: Replace deprecated entity_create()...

Issue #2609904 by timmillwood, dawehner: Replace deprecated entity_create() calls in NormalizerTestBase

core/modules/serialization/src/Tests/NormalizerTestBase.php

@@ -7,7 +7,9 @@
 
 namespace Drupal\serialization\Tests;
 
-use Drupal\simpletest\KernelTestBase;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
 
 abstract class NormalizerTestBase extends KernelTestBase {
 
@@ -29,14 +31,14 @@ protected function setUp() {
     \Drupal::moduleHandler()->invoke('rest', 'install');
 
     // Auto-create a field for testing.
-    entity_create('field_storage_config', array(
+    FieldstorageConfig::create(array(
       'entity_type' => 'entity_test_mulrev',
       'field_name' => 'field_test_text',
       'type' => 'text',
       'cardinality' => 1,
       'translatable' => FALSE,
     ))->save();
-    entity_create('field_config', array(
+    FieldConfig::create(array(
       'entity_type' => 'entity_test_mulrev',
       'field_name' => 'field_test_text',
       'bundle' => 'entity_test_mulrev',