Add support for declaration tokens

instant-xml/src/de.rs

@@ -302,6 +302,10 @@ impl<'xml> Iterator for Context<'xml> {
                 Ok(Token::Text { text }) => {
                     return Some(Ok(Node::Text(text.as_str())));
                 }
+                Ok(Token::Declaration { .. }) => match self.stack.is_empty() {
+                    false => return Some(Err(Error::UnexpectedToken(format!("{:?}", token)))),
+                    true => {}
+                },
                 Ok(token) => return Some(Err(Error::UnexpectedToken(format!("{:?}", token)))),
                 Err(e) => return Some(Err(Error::Parse(e))),
             }