Replaced DOMString constructor by conversion functions.

Replaced DOMString(...) by DOMString::from(...).
Replaced ....0 by String::from(...).
Removed any uses of .to_owner() in DOMString::from("...").

components/script/dom/namednodemap.rs

@@ -89,7 +89,7 @@ impl NamedNodeMapMethods for NamedNodeMap {
     // https://heycam.github.io/webidl/#dfn-supported-property-names
     fn SupportedPropertyNames(&self) -> Vec<DOMString> {
         self.owner.attrs().iter().map(|attr| {
-            DOMString((**attr.name()).to_owned())
+            DOMString::from(&**attr.name()) // FIXME(ajeffrey): Convert directly from &Atom to DOMString
         }).collect()
     }
 }