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

Source/core/html/parser/HTMLConstructionSite.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 74 matching lines @@
 namespace blink {
 
 // Note: These are intentionally ordered so that when we concatonate
 // strings and whitespaces the resulting whitespace is ws = min(ws1, ws2).
 enum WhitespaceMode {
     WhitespaceUnknown,
     NotAllWhitespace,
     AllWhitespace,
 };
 
+enum FlushMode {
+    MandatoryFlush,
+    FacultativeFlush, // Do not flush if there is no visible changes.

[eseidel, 2014/08/26 16:26:39]

I think you'll find more people who know the word "optional":
http://en.wikipedia.org/wiki/Facultative

But it still doesn't really tell the caller when the optional flush does
anything, or when you should call optional flush vs. mandatory flush. 
Definitely need more comments here.

Another option would be:
FlushAlways,
FlushIfAtTextLimit,

[eustas, 2014/08/27 11:31:26]

Sounds good. Thanks.

+};
+
 class AtomicHTMLToken;
 class Document;
 class Element;
 class HTMLFormElement;
 
 class HTMLConstructionSite FINAL {
     WTF_MAKE_NONCOPYABLE(HTMLConstructionSite);
     DISALLOW_ALLOCATION();
 public:
     HTMLConstructionSite(Document*, ParserContentPolicy);
     HTMLConstructionSite(DocumentFragment*, ParserContentPolicy);
     ~HTMLConstructionSite();
     void trace(Visitor*);
 
     void detach();
 
     // executeQueuedTasks empties the queue but does not flush pending text.
     // NOTE: Possible reentrancy via JavaScript execution.
     void executeQueuedTasks();
 
     // flushPendingText turns pending text into queued Text insertions, but does not execute them.
-    void flushPendingText();
+    void flushPendingText(FlushMode);
 
     // Called before every token in HTMLTreeBuilder::processToken, thus inlined:
-    void flush()
+    void flush(FlushMode mode)
     {
         if (!hasPendingTasks())
             return;
-        flushPendingText();
+        flushPendingText(mode);
         executeQueuedTasks(); // NOTE: Possible reentrancy via JavaScript execution.
         ASSERT(!hasPendingTasks());
     }
 
     bool hasPendingTasks()
     {
         return !m_pendingText.isEmpty() || !m_taskQueue.isEmpty();
     }
 
     void setDefaultCompatibilityMode();
@@ skipping 173 matching lines @@
     // "whenever a node would be inserted into the current node, it must instead
     // be foster parented."  This flag tracks whether we're in that state.
     bool m_redirectAttachToFosterParent;
 
     bool m_inQuirksMode;
 };
 
 } // namespace blink
 
 #endif