Refactoring: Have StyledMarkupAccumulator use MarkupFormatter

Source/core/editing/MarkupAccumulator.h

Index: Source/core/editing/MarkupAccumulator.h
diff --git a/Source/core/editing/MarkupAccumulator.h b/Source/core/editing/MarkupAccumulator.h
index 68e16f6849a6316cd2841e2ba4b145e119e14920..77394ba3ec395d541f7ee85f1a3abfcf17700163 100644
--- a/Source/core/editing/MarkupAccumulator.h
+++ b/Source/core/editing/MarkupAccumulator.h
@@ -53,9 +53,6 @@ public:
     void appendStartMarkup(StringBuilder&, Node&, Namespaces*);
     void appendEndMarkup(StringBuilder&, const Element&);
 
-    size_t length() const { return m_markup.length(); }
-    void concatenateMarkup(StringBuilder&) const;
-
     bool serializeAsHTMLDocument(const Node&) const;
     String toString() { return m_markup.toString(); }