Add method on Value::IsAsyncFunction to detect async functions

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 3366 matching lines @@
 bool Value::IsNativeError() const {
   return Utils::OpenHandle(this)->IsJSError();
 }
 
 
 bool Value::IsRegExp() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   return obj->IsJSRegExp();
 }
 
+bool Value::IsAsyncFunction() const {
+  i::Handle<i::Object> obj = Utils::OpenHandle(this);
+  if (!obj->IsJSFunction()) return false;
+  i::Handle<i::JSFunction> func = i::Handle<i::JSFunction>::cast(obj);
+  return func->shared()->is_async();
+}
 
 bool Value::IsGeneratorFunction() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (!obj->IsJSFunction()) return false;
   i::Handle<i::JSFunction> func = i::Handle<i::JSFunction>::cast(obj);
   return func->shared()->is_generator();
 }
 
 
 bool Value::IsGeneratorObject() const {
@@ skipping 6056 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