Remove unnecessary Document.h includes in .cpp files

Source/web/PrerendererClientImpl.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 "web/PrerendererClientImpl.h"
 
-#include "core/dom/Document.h"
 #include "platform/Prerender.h"
 #include "public/platform/WebPrerender.h"
 #include "public/web/WebPrerendererClient.h"
 #include "web/WebViewImpl.h"
 
 namespace blink {
 
 PrerendererClientImpl::PrerendererClientImpl(WebPrerendererClient* client)
     : m_client(client)
 {
 }
 
 void PrerendererClientImpl::willAddPrerender(WebCore::Prerender* prerender)
 {
     if (!m_client)
         return;
     WebPrerender webPrerender(prerender);
     m_client->willAddPrerender(&webPrerender);
 }
 
 }