Move generated bindings to script_bindings (#36323)

This is the final step of #1799, where the majority of the generated
code for the JS bindings is now compiled as part of the script_bindings
build step. The remaining pieces in script must live there because they
refer to concrete DOM types; all code in script_bindings is generic over
the
[DomTypes](https://doc.servo.org/script/dom/bindings/codegen/DomTypes/trait.DomTypes.html)
trait.

My testing with incremental builds shows me a 12 second reduction in
build times on my 2024 M4 Macbook Pro when modifying code in the script
crate after these changes. Before this PR those changes took 20 seconds
to rebuild Servo, and now they take 8 seconds.

Testing: Existing WPT tests ensure no regressions.
Fixes: #1799

---------

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

components/script_bindings/mem.rs

@@ -0,0 +1,20 @@
+/* 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/. */
+
+//! Routines for handling measuring the memory usage of arbitrary DOM nodes.
+
+use std::os::raw::c_void;
+
+use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
+
+/// Used by codegen to include the pointer to the `MallocSizeOf` implementation of each
+/// IDL interface. This way we don't have to find the most-derived interface of DOM
+/// objects by hand in code.
+#[allow(unsafe_code)]
+pub(crate) unsafe fn malloc_size_of_including_raw_self<T: MallocSizeOf>(
+    ops: &mut MallocSizeOfOps,
+    obj: *const c_void,
+) -> usize {
+    ops.malloc_size_of(obj) + (*(obj as *const T)).size_of(ops)
+}