refactor: 退役逃逸写屏障 builtins 侧调用点与 trait 兑现

crates/oxide_vm/src/vm/vmhost.rs

@@ -194,9 +194,6 @@ impl oxide_runtime_api::VmHost for Vm {
             || std::ptr::eq(p, self.async_function_proto.as_ptr())
             || std::ptr::eq(p, self.async_generator_function_proto.as_ptr())
     }
-    fn promote_if_needed_for_write_ptr(&mut self, _target_ptr: *mut JsObject, value: JsValue) -> JsValue {
-        value
-    }
     fn step_rng(&mut self) {
         self.step_rng()
     }