Quota: Add null check

Source/modules/quota/DeprecatedStorageQuota.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 67 matching lines @@
 {
     ASSERT(executionContext);
 
     blink::WebStorageQuotaType storageType = static_cast<blink::WebStorageQuotaType>(m_type);
     if (storageType != blink::WebStorageQuotaTypeTemporary && storageType != blink::WebStorageQuotaTypePersistent) {
         // Unknown storage type is requested.
         executionContext->postTask(StorageErrorCallback::CallbackTask::create(errorCallback, NotSupportedError));
         return;
     }
 
-    StorageQuotaClient::from(executionContext)->requestQuota(executionContext, storageType, newQuotaInBytes, successCallback, errorCallback);
+    StorageQuotaClient* client = StorageQuotaClient::from(executionContext);
+    if (!client) {
+        executionContext->postTask(StorageErrorCallback::CallbackTask::create(errorCallback, NotSupportedError));
+        return;
+    }
+
+    client->requestQuota(executionContext, storageType, newQuotaInBytes, successCallback, errorCallback);
 }
 
 DeprecatedStorageQuota::~DeprecatedStorageQuota()
 {
 }
 
 } // namespace WebCore