deps: v8: [objects] Determine host objects with serializer delegate

deps/v8/include/v8-value-serializer.h

@@ -75,6 +75,20 @@ class V8_EXPORT ValueSerializer {
      */
     virtual void ThrowDataCloneError(Local<String> message) = 0;
 
+    /**
+     * The embedder overrides this method to enable custom host object filter
+     * with Delegate::IsHostObject.
+     *
+     * This method is called at most once per serializer.
+     */
+    virtual bool HasCustomHostObject(Isolate* isolate);
+
+    /**
+     * The embedder overrides this method to determine if an JS object is a
+     * host object and needs to be serialized by the host.
+     */
+    virtual Maybe<bool> IsHostObject(Isolate* isolate, Local<Object> object);
+
     /**
      * The embedder overrides this method to write some kind of host object, if
      * possible. If not, a suitable exception should be thrown and

deps/v8/src/api/api.cc

@@ -3569,6 +3569,19 @@ Maybe<bool> ValueSerializer::Delegate::WriteHostObject(Isolate* v8_isolate,
   return Nothing<bool>();
 }
 
+bool ValueSerializer::Delegate::HasCustomHostObject(Isolate* v8_isolate) {
+  return false;
+}
+
+Maybe<bool> ValueSerializer::Delegate::IsHostObject(Isolate* v8_isolate,
+                                                    Local<Object> object) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
+  i::Handle<i::JSObject> js_object =
+      i::Handle<i::JSObject>::cast(Utils::OpenHandle(*object));
+  return Just<bool>(
+      i::JSObject::GetEmbedderFieldCount(js_object->map(i_isolate)));
+}
+
 Maybe<uint32_t> ValueSerializer::Delegate::GetSharedArrayBufferId(
     Isolate* v8_isolate, Local<SharedArrayBuffer> shared_array_buffer) {
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(v8_isolate);