Stop mutating Element::namespace.

src/components/script/dom/document.rs

@@ -430,7 +430,7 @@ impl<'a> DocumentMethods for JSRef<'a, Document> {
             return Err(InvalidCharacter);
         }
         let local_name = local_name.as_slice().to_ascii_lower();
-        Ok(build_element_from_tag(local_name, self))
+        Ok(build_element_from_tag(local_name, namespace::HTML, self))
     }
 
     // http://dom.spec.whatwg.org/#dom-document-createelementns
@@ -473,7 +473,7 @@ impl<'a> DocumentMethods for JSRef<'a, Document> {
         }
 
         if ns == namespace::HTML {
-            Ok(build_element_from_tag(local_name_from_qname, self))
+            Ok(build_element_from_tag(local_name_from_qname, ns, self))
         } else {
             Ok(Element::new(local_name_from_qname, ns, prefix_from_qname, self))
         }

src/components/script/dom/node.rs

@@ -1252,7 +1252,8 @@ impl Node {
             ElementNodeTypeId(..) => {
                 let element: &JSRef<Element> = ElementCast::to_ref(node).unwrap();
                 let element = element.deref();
-                let element = build_element_from_tag(element.local_name.clone(), &*document);
+                let element = build_element_from_tag(element.local_name.clone(),
+                    element.namespace.clone(), &*document);
                 NodeCast::from_temporary(element)
             },
             TextNodeTypeId => {
@@ -1289,22 +1290,16 @@ impl Node {
             },
             ElementNodeTypeId(..) => {
                 let node_elem: &JSRef<Element> = ElementCast::to_ref(node).unwrap();
-                let node_elem = node_elem.deref();
+                let copy_elem: &JSRef<Element> = ElementCast::to_ref(&*copy).unwrap();
-                let copy_elem: &mut JSRef<Element> = ElementCast::to_mut_ref(&mut *copy).unwrap();
 
-                // XXX: to avoid double borrowing compile error. we might be able to fix this after #1854
-                let copy_elem_alias = copy_elem.clone();
-
-                let copy_elem = copy_elem.deref_mut();
                 // FIXME: https://github.com/mozilla/servo/issues/1737
-                copy_elem.namespace = node_elem.namespace.clone();
                 let window = document.deref().window.root();
-                for attr in node_elem.attrs.borrow().iter().map(|attr| attr.root()) {
+                for attr in node_elem.deref().attrs.borrow().iter().map(|attr| attr.root()) {
-                    copy_elem.attrs.borrow_mut().push_unrooted(
+                    copy_elem.deref().attrs.borrow_mut().push_unrooted(
                         &Attr::new(&*window,
                                    attr.deref().local_name.clone(), attr.deref().value.clone(),
                                    attr.deref().name.clone(), attr.deref().namespace.clone(),
-                                   attr.deref().prefix.clone(), &copy_elem_alias));
+                                   attr.deref().prefix.clone(), copy_elem));
                 }
             },
             _ => ()

src/components/script/html/hubbub_html_parser.rs

@@ -17,10 +17,10 @@ use html::cssparse::{StylesheetProvenance, UrlProvenance, spawn_css_parser};
 use script_task::Page;
 
 use hubbub::hubbub;
-use hubbub::hubbub::{NullNs, XLinkNs, XmlNs, XmlNsNs};
+use hubbub::hubbub::{NullNs, HtmlNs, MathMlNs, SvgNs, XLinkNs, XmlNs, XmlNsNs};
 use servo_net::resource_task::{Load, LoadData, Payload, Done, ResourceTask, load_whole_resource};
 use servo_util::namespace;
-use servo_util::namespace::Null;
+use servo_util::namespace::{Namespace, Null};
 use servo_util::str::{DOMString, HTML_SPACE_CHARACTERS};
 use servo_util::task::spawn_named;
 use servo_util::url::parse_url;
@@ -158,7 +158,11 @@ fn js_script_listener(to_parent: Sender<HtmlDiscoveryMessage>,
 // Silly macros to handle constructing      DOM nodes. This produces bad code and should be optimized
 // via atomization (issue #85).
 
-pub fn build_element_from_tag(tag: DOMString, document: &JSRef<Document>) -> Temporary<Element> {
+pub fn build_element_from_tag(tag: DOMString, ns: Namespace, document: &JSRef<Document>) -> Temporary<Element> {
+    if ns != namespace::HTML {
+        return Element::new(tag, ns, None, document);
+    }
+
     // TODO (Issue #85): use atoms
     handle_element!(document, tag, "a",         HTMLAnchorElement);
     handle_element!(document, tag, "abbr",      HTMLElement);
@@ -369,7 +373,13 @@ pub fn parse_html(page: &Page,
             // NOTE: tmp vars are workaround for lifetime issues. Both required.
             let tmp_borrow = doc_cell.borrow();
             let tmp = &*tmp_borrow;
-            let mut element: Root<Element> = build_element_from_tag(tag.name.clone(), *tmp).root();
+            let namespace = match tag.ns {
+                HtmlNs => namespace::HTML,
+                MathMlNs => namespace::MathML,
+                SvgNs => namespace::SVG,
+                ns => fail!("Not expecting namespace {:?}", ns),
+            };
+            let mut element: Root<Element> = build_element_from_tag(tag.name.clone(), namespace, *tmp).root();
 
             debug!("-- attach attrs");
             for attr in tag.attributes.iter() {