[WebSocket] Remove unnecessary harmful check on the Page instance associated with the Document

Source/modules/websockets/DocumentWebSocketChannel.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 103 matching lines @@
     : ContextLifecycleObserver(context)
     , m_handle(adoptPtr(handle ? handle : Platform::current()->createWebSocketHandle()))
     , m_client(client)
     , m_identifier(0)
     , m_sendingQuota(0)
     , m_receivedDataSizeForFlowControl(receivedDataSizeForFlowControlHighWaterMark * 2) // initial quota
     , m_sentSizeOfTopMessage(0)
     , m_sourceURLAtConstruction(sourceURL)
     , m_lineNumberAtConstruction(lineNumber)
 {
-    if (context->isDocument() && toDocument(context)->page())
+    if (context->isDocument())
         m_identifier = createUniqueIdentifier();
 }
 
 DocumentWebSocketChannel::~DocumentWebSocketChannel()
 {
     ASSERT(!m_blobLoader);
 }
 
 bool DocumentWebSocketChannel::connect(const KURL& url, const String& protocol)
 {
@@ skipping 453 matching lines @@
 }
 
 void DocumentWebSocketChannel::trace(Visitor* visitor)
 {
     visitor->trace(m_blobLoader);
     visitor->trace(m_client);
     WebSocketChannel::trace(visitor);
 }
 
 } // namespace blink