Refactoring: Remove StyledMarkupAccumulator::appendString and add appendNewLine

Source/core/editing/StyledMarkupAccumulator.h

Index: Source/core/editing/StyledMarkupAccumulator.h
diff --git a/Source/core/editing/StyledMarkupAccumulator.h b/Source/core/editing/StyledMarkupAccumulator.h
index 5a00af9e5877d9d959c846e63ba9a098b5420112..de91b222baa69de7627dc0caa01e382408eefac4 100644
--- a/Source/core/editing/StyledMarkupAccumulator.h
+++ b/Source/core/editing/StyledMarkupAccumulator.h
@@ -48,9 +48,9 @@ public:
 
     StyledMarkupAccumulator(EAbsoluteURLs, const TextOffset& start, const TextOffset& end, const PassRefPtrWillBeRawPtr<Document>, EAnnotateForInterchange, Node*);
 
-    void appendString(const String&);
     void appendStartTag(Node&);
     void appendEndTag(const Element&);
+    void appendInterchangeNewline();
 
     // TODO(hajimehoshi): These functions are called from the serializer, but
     // should not.