Add charset method.

mailnews/base/src/nsMessenger.cpp

@@ -125,6 +125,7 @@ public:
   NS_IMETHOD Undo();
   NS_IMETHOD Redo();
   NS_IMETHOD SendUnsentMessages();
+  NS_IMETHOD SetDocumentCharset(const PRUnichar *characterSet);
 
 protected:
 	nsresult DoDelete(nsIRDFCompositeDataSource* db, nsISupportsArray *srcArray, nsISupportsArray *deletedArray);
@@ -891,3 +892,8 @@ nsMessenger::SendUnsentMessages()
 	} 
 	return NS_OK;
 }
+
+NS_IMETHODIMP nsMessenger::SetDocumentCharset(const PRUnichar *characterSet)
+{
+	return NS_OK;
+}