some minor improvements

lib/runtime-core/src/import.rs

@@ -54,6 +54,7 @@ impl IsExport for Export {
 ///     n
 /// }
 /// ```
+#[derive(Clone)]
 pub struct ImportObject {
     map: Arc<Mutex<HashMap<String, Box<dyn LikeNamespace + Send>>>>,
     pub(crate) state_creator:
@@ -158,15 +159,6 @@ impl ImportObject {
             .and_then(|ns| f(ns))
     }
 
-    /// Create a clone ref of this namespace.
-    pub fn clone_ref(&self) -> Self {
-        Self {
-            map: Arc::clone(&self.map),
-            state_creator: self.state_creator.clone(),
-            allow_missing_functions: false,
-        }
-    }
-
     fn get_objects(&self) -> VecDeque<(String, String, Export)> {
         let mut out = VecDeque::new();
         let guard = self.map.lock().unwrap();

lib/runtime-core/src/instance.rs

@@ -103,7 +103,7 @@ impl Instance {
             module,
             inner,
             exports,
-            import_object: imports.clone_ref(),
+            import_object: imports.clone(),
         };
 
         if let Some(start_index) = instance.module.info.start_func {