Copy item path rather than full use statement.

src/librustdoc/html/static/js/main.js

@@ -985,7 +985,7 @@ function hideThemeButtonState() {
         });
 
         var el = document.createElement('textarea');
-        el.value = 'use ' + path.join('::') + ';';
+        el.value = path.join('::');
         el.setAttribute('readonly', '');
         // To not make it appear on the screen.
         el.style.position = 'absolute';