Include Document.h in fewer headers

Source/core/html/HTMLShadowElement.cpp

 /*
  * Copyright (C) 2012 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 14 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/html/HTMLShadowElement.h"
 
 #include "core/HTMLNames.h"
+#include "core/dom/Document.h"
 #include "core/dom/shadow/ShadowRoot.h"
 
 namespace WebCore {
 
 class Document;
 
 inline HTMLShadowElement::HTMLShadowElement(Document& document)
     : InsertionPoint(HTMLNames::shadowTag, document)
 {
     ScriptWrappable::init(this);
@@ skipping 29 matching lines @@
         if (root && root->olderShadowRoot() && root->type() != root->olderShadowRoot()->type()) {
             String message = String::format("<shadow> doesn't work for %s element host.", root->host()->tagName().utf8().data());
             document().addConsoleMessage(RenderingMessageSource, WarningMessageLevel, message);
         }
     }
     return InsertionPoint::insertedInto(insertionPoint);
 }
 
 } // namespace WebCore