node-api: allow napi_delete_reference in finalizers

`napi_delete_reference` must be called immediately for a
`napi_reference` returned from `napi_wrap` in the corresponding
finalizer, in order to clean up the `napi_reference` timely.

`napi_delete_reference` is safe to be invoked during GC.

src/js_native_api_v8.cc

@@ -2769,10 +2769,12 @@ napi_status NAPI_CDECL napi_create_reference(napi_env env,
 
 // Deletes a reference. The referenced value is released, and may be GC'd unless
 // there are other references to it.
+// For a napi_reference returned from `napi_wrap`, this must be called in the
+// finalizer.
 napi_status NAPI_CDECL napi_delete_reference(napi_env env, napi_ref ref) {
   // Omit NAPI_PREAMBLE and GET_RETURN_STATUS because V8 calls here cannot throw
   // JS exceptions.
-  CHECK_ENV_NOT_IN_GC(env);
+  CHECK_ENV(env);
   CHECK_ARG(env, ref);
 
   delete reinterpret_cast<v8impl::Reference*>(ref);

test/js-native-api/6_object_wrap/6_object_wrap.cc

@@ -10,8 +10,9 @@ MyObject::MyObject(double value)
 
 MyObject::~MyObject() { napi_delete_reference(env_, wrapper_); }
 
-void MyObject::Destructor(
-  napi_env env, void* nativeObject, void* /*finalize_hint*/) {
+void MyObject::Destructor(node_api_basic_env env,
+                          void* nativeObject,
+                          void* /*finalize_hint*/) {
   MyObject* obj = static_cast<MyObject*>(nativeObject);
   delete obj;
 }
@@ -154,7 +155,7 @@ napi_value MyObject::Multiply(napi_env env, napi_callback_info info) {
 }
 
 // This finalizer should never be invoked.
-void ObjectWrapDanglingReferenceFinalizer(napi_env env,
+void ObjectWrapDanglingReferenceFinalizer(node_api_basic_env env,
                                           void* finalize_data,
                                           void* finalize_hint) {
   assert(0 && "unreachable");

test/js-native-api/6_object_wrap/binding.gyp

@@ -5,6 +5,13 @@
       "sources": [
         "6_object_wrap.cc"
       ]
+    },
+    {
+      "target_name": "6_object_wrap_basic_finalizer",
+      "defines": [ "NAPI_EXPERIMENTAL" ],
+      "sources": [
+        "6_object_wrap.cc"
+      ]
     }
   ]
 }

test/js-native-api/6_object_wrap/myobject.h

@@ -6,7 +6,9 @@
 class MyObject {
  public:
   static void Init(napi_env env, napi_value exports);
-  static void Destructor(napi_env env, void* nativeObject, void* finalize_hint);
+  static void Destructor(node_api_basic_env env,
+                         void* nativeObject,
+                         void* finalize_hint);
 
  private:
   explicit MyObject(double value_ = 0);

test/js-native-api/6_object_wrap/test-basic-finalizer.js

@@ -0,0 +1,20 @@
+// Flags: --expose-gc
+
+'use strict';
+const common = require('../../common');
+const addon = require(`./build/${common.buildType}/6_object_wrap_basic_finalizer`);
+const { onGC } = require('../../common/gc');
+
+/**
+ * This test verifies that an ObjectWrap can be correctly finalized with an NAPI_EXPERIMENTAL
+ * node_api_basic_finalizer.
+ */
+
+{
+  let obj = new addon.MyObject(9);
+  onGC(obj, {
+    ongc: common.mustCall(),
+  });
+  obj = null;
+  global.gc();
+}