Move more foundational types to script_bindings (#35280)

* script: Move DOMClass to script_bindings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* script: Move DOMJSClass and get_dom_class to script_bindings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* script: Move Castable/DerivedFrom/IDLInterface to script_bindings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

---------

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

components/script_bindings/utils.rs

@@ -0,0 +1,48 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+use std::os::raw::c_void;
+
+use malloc_size_of::MallocSizeOfOps;
+
+use crate::codegen::Globals::Globals;
+use crate::codegen::InheritTypes::TopTypeId;
+use crate::codegen::PrototypeList::{self, MAX_PROTO_CHAIN_LENGTH};
+
+/// The struct that holds inheritance information for DOM object reflectors.
+#[derive(Clone, Copy)]
+pub struct DOMClass {
+    /// A list of interfaces that this object implements, in order of decreasing
+    /// derivedness.
+    pub interface_chain: [PrototypeList::ID; MAX_PROTO_CHAIN_LENGTH],
+
+    /// The last valid index of `interface_chain`.
+    pub depth: u8,
+
+    /// The type ID of that interface.
+    pub type_id: TopTypeId,
+
+    /// The MallocSizeOf function wrapper for that interface.
+    pub malloc_size_of: unsafe fn(ops: &mut MallocSizeOfOps, *const c_void) -> usize,
+
+    /// The `Globals` flag for this global interface, if any.
+    pub global: Globals,
+}
+unsafe impl Sync for DOMClass {}
+
+/// The JSClass used for DOM object reflectors.
+#[derive(Copy)]
+#[repr(C)]
+pub struct DOMJSClass {
+    /// The actual JSClass.
+    pub base: js::jsapi::JSClass,
+    /// Associated data for DOM object reflectors.
+    pub dom_class: DOMClass,
+}
+impl Clone for DOMJSClass {
+    fn clone(&self) -> DOMJSClass {
+        *self
+    }
+}
+unsafe impl Sync for DOMJSClass {}