Revert of Revert of HTMLConstructionSite: avoid n^2 running time for large scripts.

Source/core/html/parser/HTMLTreeBuilder.h

 /*
  * Copyright (C) 2010 Google, Inc. All Rights Reserved.
  * Copyright (C) 2011 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 64 matching lines @@
 
     void constructTree(AtomicHTMLToken*);
 
     bool hasParserBlockingScript() const { return !!m_scriptToProcess; }
     // Must be called to take the parser-blocking script before calling the parser again.
     PassRefPtrWillBeRawPtr<Element> takeScriptToProcess(TextPosition& scriptStartPosition);
 
     // Done, close any open tags, etc.
     void finished();
 
-    // Synchronously empty any queues, possibly creating more DOM nodes.
-    void flush() { m_tree.flush(); }
+    // Synchronously flush pending text and queued tasks, possibly creating more DOM nodes.
+    // Flushing pending text depends on |mode|.
+    void flush(FlushMode mode) { m_tree.flush(mode); }
 
     void setShouldSkipLeadingNewline(bool shouldSkip) { m_shouldSkipLeadingNewline = shouldSkip; }
 
 private:
     class CharacterTokenBuffer;
     // Represents HTML5 "insertion mode"
     // http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#insertion-mode
     enum InsertionMode {
         InitialMode,
         BeforeHTMLMode,
@@ skipping 142 matching lines @@
 
     RefPtrWillBeMember<Element> m_scriptToProcess; // <script> tag which needs processing before resuming the parser.
     TextPosition m_scriptToProcessStartPosition; // Starting line number of the script tag needing processing.
 
     HTMLParserOptions m_options;
 };
 
 }
 
 #endif