XMLHttpRequest: Factor out decorder/document init

Source/core/xml/XMLHttpRequest.h

Index: Source/core/xml/XMLHttpRequest.h
diff --git a/Source/core/xml/XMLHttpRequest.h b/Source/core/xml/XMLHttpRequest.h
index a17d17314b2b614e6ebced02c1dde15843217c60..d2060c8c27ee07eae3983a779c186437975e60f5 100644
--- a/Source/core/xml/XMLHttpRequest.h
+++ b/Source/core/xml/XMLHttpRequest.h
@@ -163,6 +163,9 @@ private:
     AtomicString responseMIMEType() const;
     bool responseIsXML() const;
 
+    PassOwnPtr<TextResourceDecoder> createDecoder() const;
+
+    void initResponseDocument();
     bool areMethodAndURLValidForSend();
 
     bool initSend(ExceptionState&);
@@ -252,7 +255,7 @@ private:
     bool m_includeCredentials;
     // Used to skip m_responseDocument creation if it's done previously. We need
     // this separate flag since m_responseDocument can be 0 for some cases.
-    bool m_createdDocument;
+    bool m_parsedResponse;
     bool m_error;
     bool m_uploadEventsAllowed;
     bool m_uploadComplete;