No tracing of nop traceable fields (#29926)

* Add `no_trace` option to JSTraceable derive

* NoTrace wrapper

* Port some types to no_trace schematics

* Fixing my unsafe mistakes (not tracing traceables)

* Add docs & safety guards for no_trace

Safety guards (trait shenanigans) guarantees safety usage of `no_trace`

* Port canvas_traits to no_trace

* Port servo_media to no_trace

* Port net_traits to no_trace

* Port style to no_trace

* Port webgpu to no_trace

* Port script_traits to no_trace

* Port canvas_traits, devtools_traits, embedder_traits, profile_traits to no_trace

* unrooted_must_root lint in seperate file

* Add trace_in_no_trace_lint as script_plugin

* Composable types in must_not_have_traceable

* Introduced HashMapTracedValues wrapper

* `HashMap<NoTrace<K>,V>`->`HashMapTracedValues<K,V>`

* Port rest of servo's types to no_trace

* Port html5ever, euclid, mime and http to no_trace

* Port remaining externals to no_trace

* Port webxr and Arc<Mutex<_>>

* Fix spelling in notrace doc

components/script/lib.rs

@@ -8,10 +8,17 @@
 #![feature(register_tool)]
 #![deny(unsafe_code)]
 #![doc = "The script crate contains all matters DOM."]
-#![cfg_attr(not(feature = "unrooted_must_root_lint"), allow(unknown_lints))]
+#![cfg_attr(
+    not(any(
+        feature = "unrooted_must_root_lint",
+        feature = "trace_in_no_trace_lint"
+    )),
+    allow(unknown_lints)
+)]
 #![allow(deprecated)] // FIXME: Can we make `allow` only apply to the `plugin` crate attribute?
 #![plugin(script_plugins)]
 #![register_tool(unrooted_must_root_lint)]
+#![register_tool(trace_in_no_trace_lint)]
 
 #[macro_use]
 extern crate bitflags;