rustdoc: clean up CSS for All Items and All Crates lists

This reduces the amount of CSS, and makes these two pages more consistent
(which, necessarily, means changing them a bit).

src/librustdoc/html/render/write_shared.rs

@@ -519,12 +519,12 @@ if (typeof exports !== 'undefined') {exports.searchIndex = searchIndex};
             let content = format!(
                 "<h1 class=\"fqn\">\
                      <span class=\"in-band\">List of all crates</span>\
-                </h1><ul class=\"crate mod\">{}</ul>",
+                </h1><ul class=\"all-items\">{}</ul>",
                 krates
                     .iter()
                     .map(|s| {
                         format!(
-                            "<li><a class=\"crate mod\" href=\"{}index.html\">{}</a></li>",
+                            "<li><a href=\"{}index.html\">{}</a></li>",
                             ensure_trailing_slash(s),
                             s
                         )