Expose IsConstructor to the C++ API

src/api.cc

 // Copyright 2012 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 "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 4345 matching lines @@
   auto self = Utils::OpenHandle(this);
   return i::JSReceiver::GetOrCreateIdentityHash(self)->value();
 }
 
 
 bool v8::Object::IsCallable() {
   auto self = Utils::OpenHandle(this);
   return self->IsCallable();
 }
 
+bool v8::Object::IsConstructor() {
+  auto self = Utils::OpenHandle(this);
+  return self->IsConstructor();
+}
 
 MaybeLocal<Value> Object::CallAsFunction(Local<Context> context,
                                          Local<Value> recv, int argc,
                                          Local<Value> argv[]) {
   PREPARE_FOR_EXECUTION_WITH_CALLBACK(context, "v8::Object::CallAsFunction()",
                                       Value);
   i::TimerEventScope<i::TimerEventExecute> timer_scope(isolate);
   TRACE_EVENT0("v8", "V8.Execute");
   auto self = Utils::OpenHandle(this);
   auto recv_obj = Utils::OpenHandle(*recv);
@@ skipping 4425 matching lines @@
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 }  // namespace internal
 }  // namespace v8