Remove DocumentParser::flush which is not used by anyone.

third_party/WebKit/Source/core/dom/DocumentParser.h

 /*
  * Copyright (C) 2000 Peter Kelly (pmk@post.com)
  * Copyright (C) 2005, 2006 Apple Computer, Inc.
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  * Copyright (C) 2010 Google, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 87 matching lines @@
     // FIXME: The names are not very accurate :(
     virtual void suspendScheduledTasks();
     virtual void resumeScheduledTasks();
 
     void addClient(DocumentParserClient*);
     void removeClient(DocumentParserClient*);
 
 protected:
     explicit DocumentParser(Document*);
 
-    virtual void flush() = 0;
-
 private:
     enum ParserState {
         ParsingState,
         StoppingState,
         StoppedState,
         DetachedState
     };
     ParserState m_state;
     bool m_documentWasLoadedAsPartOfNavigation;
 
     // Every DocumentParser needs a pointer back to the document.
     // m_document will be 0 after the parser is stopped.
     RawPtrWillBeMember<Document> m_document;
 
     WillBeHeapHashSet<RawPtrWillBeWeakMember<DocumentParserClient>> m_clients;
 };
 
 } // namespace blink
 
 #endif // DocumentParser_h