Deny unsafe blocks in script.

As a first start, this allows them indiscriminately where used.

components/script/parse/html.rs

@@ -2,6 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#![allow(unsafe_blocks)]
+
 use dom::attr::AttrHelpers;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::codegen::InheritTypes::{NodeCast, ElementCast, HTMLScriptElementCast};