[Wasm] Lower complex external declarations

- Properties
- Member functions
- Object declarations
- Constructors
- Classes with instance checks

compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/JsMapping.kt

@@ -45,6 +45,15 @@ class JsMapping(val state: JsMappingState) : DefaultMapping(state) {
     // Wasm mappings
     val wasmJsInteropFunctionToWrapper =
         state.newDeclarationToDeclarationMapping<IrSimpleFunction, IrSimpleFunction>()
+
+    val wasmNestedExternalToNewTopLevelFunction =
+        state.newDeclarationToDeclarationMapping<IrFunction, IrSimpleFunction>()
+
+    val wasmExternalObjectToGetInstanceFunction =
+        state.newDeclarationToDeclarationMapping<IrClass, IrSimpleFunction>()
+
+    val wasmExternalClassToInstanceCheck =
+        state.newDeclarationToDeclarationMapping<IrClass, IrSimpleFunction>()
 }