Auto merge of #23676 - servo:check, r=Manishearth

Share more `./mach build` logic with mach check, doc, test-unit

Fixes #23659

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components/script/dom/bindings/conversions.rs

@@ -69,10 +69,7 @@ pub trait IDLInterface {
 }
 
 /// A trait to mark an IDL interface as deriving from another one.
-#[cfg_attr(
-    feature = "unstable",
-    rustc_on_unimplemented(message = "The IDL interface `{Self}` is not derived from `{T}`.")
-)]
+#[rustc_on_unimplemented(message = "The IDL interface `{Self}` is not derived from `{T}`.")]
 pub trait DerivedFrom<T: Castable>: Castable {}
 
 impl<T: Float + ToJSValConvertible> ToJSValConvertible for Finite<T> {

components/script/dom/bindings/root.rs

@@ -330,13 +330,13 @@ impl<T: DomObject> Deref for Dom<T> {
 
 unsafe impl<T: DomObject> JSTraceable for Dom<T> {
     unsafe fn trace(&self, trc: *mut JSTracer) {
-        #[cfg(all(feature = "unstable", debug_assertions))]
-        let trace_str = format!("for {} on heap", ::std::intrinsics::type_name::<T>());
-        #[cfg(all(feature = "unstable", debug_assertions))]
-        let trace_info = &trace_str[..];
-        #[cfg(not(all(feature = "unstable", debug_assertions)))]
-        let trace_info = "for DOM object on heap";
-
+        let trace_string;
+        let trace_info = if cfg!(debug_assertions) {
+            trace_string = format!("for {} on heap", ::std::intrinsics::type_name::<T>());
+            &trace_string[..]
+        } else {
+            "for DOM object on heap"
+        };
         trace_reflector(trc, trace_info, (*self.ptr.as_ptr()).reflector());
     }
 }

components/script/dom/window.rs

@@ -938,10 +938,7 @@ impl WindowMethods for Window {
 
     #[allow(unsafe_code)]
     fn Trap(&self) {
-        #[cfg(feature = "unstable")]
-        unsafe {
-            ::std::intrinsics::breakpoint()
-        }
+        unsafe { ::std::intrinsics::breakpoint() }
     }
 
     #[allow(unsafe_code)]