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..30c1768beefa5b8e6333a099d9151f083a1f9412 100644
--- a/Source/core/html/parser/HTMLConstructionSite.h
+++ b/Source/core/html/parser/HTMLConstructionSite.h
@@ -92,6 +92,14 @@ enum WhitespaceMode {
     AllWhitespace,
 };
 
+enum FlushMode {
+    // Flush pending text. Flush queued tasks.
+    FlushAlways,
+
+    // Flush pending text if node has length limit. Flush queued tasks.
+    FlushIfAtTextLimit,
+};
+
 class AtomicHTMLToken;
 class Document;
 class Element;
@@ -113,14 +121,14 @@ public:
     void executeQueuedTasks();
 
     // flushPendingText turns pending text into queued Text insertions, but does not execute them.
-    void flushPendingText();
+    void flushPendingText(FlushMode);

[kouhei (in TOK), 2014/09/02 15:56:06]

Nit: Can we make this method private? It is confusing to have both
flushPendingText() and flush() exposed to user, and flushPendingText() seems to
be only used internally.

 
     // 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());
     }