Introduce a script_layout_interface crate and move RestyleDamage to it.

components/script_layout_interface/lib.rs

@@ -0,0 +1,18 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+//! This module contains traits in script used generically in the rest of Servo.
+//! The traits are here instead of in script so that these modules won't have
+//! to depend on script.
+
+#![deny(unsafe_code)]
+#![feature(plugin)]
+#![plugin(plugins)]
+
+#[allow(unused_extern_crates)]
+#[macro_use]
+extern crate bitflags;
+extern crate style;
+
+pub mod restyle_damage;