Import the util crate as util rather than servo_util.

This used to conflict with the util crate from the standard library, which
has long since been removed.

The import in layout has not been changed because of a conflict with the
util mod there.

components/script/dom/htmlquoteelement.rs

@@ -10,7 +10,7 @@ use dom::eventtarget::{EventTarget, EventTargetTypeId};
 use dom::element::ElementTypeId;
 use dom::htmlelement::{HTMLElement, HTMLElementTypeId};
 use dom::node::{Node, NodeTypeId};
-use servo_util::str::DOMString;
+use util::str::DOMString;
 
 #[dom_struct]
 pub struct HTMLQuoteElement {