Separate @viewport from other RuleSet construction.

third_party/WebKit/Source/core/dom/DocumentStyleSheetCollection.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)
@@ skipping 21 matching lines @@
 
 #include "core/dom/TreeScopeStyleSheetCollection.h"
 #include "platform/heap/WrapperVisitor.h"
 
 namespace blink {
 
 class DocumentStyleSheetCollector;
 class StyleEngine;
 class TreeScope;
 
-class DocumentStyleSheetCollection final
+class CORE_EXPORT DocumentStyleSheetCollection final
     : public TreeScopeStyleSheetCollection {
   WTF_MAKE_NONCOPYABLE(DocumentStyleSheetCollection);
 
  public:
   static DocumentStyleSheetCollection* create(TreeScope& treeScope) {
     return new DocumentStyleSheetCollection(treeScope);
   }
 
   void updateActiveStyleSheets(StyleEngine&, StyleResolverUpdateMode);
   void collectStyleSheets(StyleEngine&, DocumentStyleSheetCollector&);
+  void updateViewport();
 
   DEFINE_INLINE_VIRTUAL_TRACE() {
     TreeScopeStyleSheetCollection::trace(visitor);
   }
 
   DECLARE_VIRTUAL_TRACE_WRAPPERS();
 
  private:
   explicit DocumentStyleSheetCollection(TreeScope&);
 
   void collectStyleSheetsFromCandidates(StyleEngine&,
                                         DocumentStyleSheetCollector&);
 };
 
 }  // namespace blink
 
 #endif