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

Source/core/html/parser/HTMLConstructionSite.h

Index: Source/core/html/parser/HTMLConstructionSite.h
diff --git a/Source/core/html/parser/HTMLConstructionSite.h b/Source/core/html/parser/HTMLConstructionSite.h
index 48be3b05cd51924a4c44ada45cacdb078eef3c85..63d1dd27cdba9144b32f6b340a5c2f494d4a7c2f 100644
--- a/Source/core/html/parser/HTMLConstructionSite.h
+++ b/Source/core/html/parser/HTMLConstructionSite.h
@@ -92,6 +92,11 @@ enum WhitespaceMode {
     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;
@@ -113,14 +118,14 @@ public:
     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());
     }