Make FunctionTemplate::HasInstance checks work with remote contexts.

test/unittests/api/remote-object-unittest.cc

+// Copyright 2017 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+#include "include/v8.h"
+#include "test/unittests/test-utils.h"
+
+namespace v8 {
+
+typedef TestWithIsolate RemoteObjectTest;
+
+namespace {
+
+bool AccessCheck(Local<Context> accessing_context,
+                 Local<Object> accessed_object, Local<Value> data) {
+  return false;
+}
+
+void NamedGetter(Local<Name> property,
+                 const PropertyCallbackInfo<Value>& info) {}
+
+void Constructor(const FunctionCallbackInfo<Value>& info) {
+  ASSERT_TRUE(info.IsConstructCall());
+}
+
+}  // namespace
+
+TEST_F(RemoteObjectTest, RemoteContextInstanceChecks) {
+  Local<FunctionTemplate> parent_template =
+      FunctionTemplate::New(isolate(), Constructor);
+
+  Local<FunctionTemplate> constructor_template =
+      FunctionTemplate::New(isolate(), Constructor);
+  constructor_template->InstanceTemplate()->SetAccessCheckCallbackAndHandler(
+      AccessCheck, NamedPropertyHandlerConfiguration(NamedGetter),
+      IndexedPropertyHandlerConfiguration());
+  constructor_template->Inherit(parent_template);
+
+  Local<Object> remote_context =
+      Context::NewRemoteContext(isolate(),
+                                    constructor_template->InstanceTemplate())
+          .ToLocalChecked();
+  EXPECT_TRUE(parent_template->HasInstance(remote_context));
+  EXPECT_TRUE(constructor_template->HasInstance(remote_context));
+
+  EXPECT_EQ(remote_context,
+            remote_context->FindInstanceInPrototypeChain(parent_template));
+  EXPECT_EQ(remote_context,
+            remote_context->FindInstanceInPrototypeChain(constructor_template));
+}
+
+}  // namespace v8