Make #[dom_struct] a proc_macro attribute

components/script/dom/htmltextareaelement.rs

@@ -25,6 +25,7 @@ use dom::node::{document_from_node, window_from_node};
 use dom::nodelist::NodeList;
 use dom::validation::Validatable;
 use dom::virtualmethods::VirtualMethods;
+use dom_struct::dom_struct;
 use html5ever_atoms::LocalName;
 use ipc_channel::ipc::IpcSender;
 use script_traits::ScriptMsg as ConstellationMsg;