Componentization: make core/dom visible for blink_web and blink_tests.

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 182 matching lines @@
     PluginDocumentClass = 1 << 3,
     MediaDocumentClass = 1 << 4,
     SVGDocumentClass = 1 << 5,
     XMLDocumentClass = 1 << 6,
 };
 
 using DocumentClassFlags = unsigned char;
 
 class Document;
 
-class DocumentVisibilityObserver : public WillBeGarbageCollectedMixin {
+class CORE_EXPORT DocumentVisibilityObserver : public WillBeGarbageCollectedMixin {
 public:
     DocumentVisibilityObserver(Document&);
     virtual ~DocumentVisibilityObserver();
 
     virtual void didChangeVisibilityState(PageVisibilityState) = 0;
 
     // Classes that inherit Node and DocumentVisibilityObserver must have a
     // virtual override of Node::didMoveToNewDocument that calls
     // DocumentVisibilityObserver::setDocument
     void setObservedDocument(Document&);
@@ skipping 1232 matching lines @@
 }
 
 Node* eventTargetNodeForDocument(Document*);
 
 DEFINE_TYPE_CASTS(TreeScope, Document, document, true, true);
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
-void showLiveDocumentInstances();
+CORE_EXPORT void showLiveDocumentInstances();
 #endif
 
 #endif // Document_h