Pass implementation object to supplemental classes by reference

Source/web/WorkerPermissionClient.cpp

 /*
  * Copyright (C) 2013 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 57 matching lines @@
     if (!m_proxy)
         return true;
     return m_proxy->allowIndexedDB(name);
 }
 
 const char* WorkerPermissionClient::supplementName()
 {
     return "WorkerPermissionClient";
 }
 
-WorkerPermissionClient* WorkerPermissionClient::from(ExecutionContext* context)
+WorkerPermissionClient* WorkerPermissionClient::from(ExecutionContext& context)
 {
-    return static_cast<WorkerPermissionClient*>(Supplement<WorkerClients>::from(toWorkerGlobalScope(context)->clients(), supplementName()));
+    WorkerClients* clients = toWorkerGlobalScope(context).clients();
+    ASSERT(clients);
+    return static_cast<WorkerPermissionClient*>(Supplement<WorkerClients>::from(*clients, supplementName()));
 }
 
 WorkerPermissionClient::WorkerPermissionClient(PassOwnPtr<WebWorkerPermissionClientProxy> proxy)
     : m_proxy(proxy)
 {
 }
 
 void providePermissionClientToWorker(WorkerClients* clients, PassOwnPtr<WebWorkerPermissionClientProxy> proxy)
 {
-    WorkerPermissionClient::provideTo(clients, WorkerPermissionClient::supplementName(), WorkerPermissionClient::create(proxy));
+    ASSERT(clients);
+    WorkerPermissionClient::provideTo(*clients, WorkerPermissionClient::supplementName(), WorkerPermissionClient::create(proxy));
 }
 
 } // namespace blink