CSP: Replace 'static_cast' with 'toDocument'.

Source/core/dom/Document.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 1353 matching lines @@
 }
 
 inline bool Document::shouldOverrideLegacyDescription(ViewportDescription::Type origin)
 {
     // The different (legacy) meta tags have different priorities based on the type
     // regardless of which order they appear in the DOM. The priority is given by the
     // ViewportDescription::Type enum.
     return origin >= m_legacyViewportDescription.type;
 }
 
+DEFINE_TYPE_CASTS(Document, ExecutionContextClient, client, client->isDocument(), client.isDocument());
 DEFINE_TYPE_CASTS(Document, ExecutionContext, context, context->isDocument(), context.isDocument());
 DEFINE_NODE_TYPE_CASTS(Document, isDocumentNode());
 
 #define DEFINE_DOCUMENT_TYPE_CASTS(thisType) \
     DEFINE_TYPE_CASTS(thisType, Document, document, document->is##thisType(), document.is##thisType())
 
 // All these varations are needed to avoid ambiguous overloads with the Node and TreeScope versions.
 inline bool operator==(const Document& a, const Document& b) { return &a == &b; }
 inline bool operator==(const Document& a, const Document* b) { return &a == b; }
 inline bool operator==(const Document* a, const Document& b) { return a == &b; }
 inline bool operator!=(const Document& a, const Document& b) { return !(a == b); }
 inline bool operator!=(const Document& a, const Document* b) { return !(a == b); }
 inline bool operator!=(const Document* a, const Document& b) { return !(a == b); }
 
 // Put these methods here, because they require the Document definition, but we really want to inline them.
 
 inline bool Node::isDocumentNode() const
 {
     return this == document();
 }
 
 Node* eventTargetNodeForDocument(Document*);
 
 } // namespace WebCore
 
 #endif // Document_h