script_bindings: Assert that serializable/transferable types have accurate WebIDL annotations (#38615)

These changes add compile-time assertions that:
* any type that implements the Serializable/Transferable trait has a
`[Serializable]` or `[Transferable]` annotation in the interface WebIDL
* any WebIDL interface with the `[Serializable]` or `[Transferable]`
annotation implements the corresponding trait

This is useful because it means that WebIDL definitions will be less
confusing if you're trying to figure out whether Servo supports
serializing/transferring a particular interface type. It also makes
fixing #21715 in the future a little bit easier, because the annotations
will remain up to date.

Testing: compile-time only; no point in writing tests for this since it
involves webidl codegen.

---------

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

components/script_bindings/webidls/CryptoKey.webidl

@@ -8,7 +8,7 @@ enum KeyType { "public", "private", "secret" };
 
 enum KeyUsage { "encrypt", "decrypt", "sign", "verify", "deriveKey", "deriveBits", "wrapKey", "unwrapKey" };
 
-[SecureContext, Exposed=(Window,Worker), Serializable, Pref="dom_crypto_subtle_enabled"]
+[SecureContext, Exposed=(Window,Worker), /*Serializable,*/ Pref="dom_crypto_subtle_enabled"]
 interface CryptoKey {
   readonly attribute KeyType type;
   readonly attribute boolean extractable;