Use instance type in Object::IsErrorObject().

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 2990 matching lines @@
         value == i::FastUI2D(i::FastD2UI(value));
   }
   return false;
 }
 
 
 bool Value::IsNativeError() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   if (!obj->IsJSObject()) return false;
   i::Handle<i::JSObject> js_obj = i::Handle<i::JSObject>::cast(obj);
-  i::Isolate* isolate = js_obj->GetIsolate();
-  i::Handle<i::Object> constructor(js_obj->map()->GetConstructor(), isolate);
-  if (!constructor->IsJSFunction()) return false;
-  i::Handle<i::JSFunction> function =
-      i::Handle<i::JSFunction>::cast(constructor);
-  if (!function->shared()->native()) return false;
-  return function.is_identical_to(isolate->error_function()) ||
-         function.is_identical_to(isolate->eval_error_function()) ||
-         function.is_identical_to(isolate->range_error_function()) ||
-         function.is_identical_to(isolate->reference_error_function()) ||
-         function.is_identical_to(isolate->syntax_error_function()) ||
-         function.is_identical_to(isolate->type_error_function()) ||
-         function.is_identical_to(isolate->uri_error_function());
+  return js_obj->map()->instance_type() == i::JS_ERROR_TYPE;

[jochen (gone - plz use gerrit), 2016/06/23 14:42:15]

why not just 

auto self = Utils::OpenHandle(this);
return i::Object::IsErrorObject(self);

 }
 
 
 bool Value::IsRegExp() const {
   i::Handle<i::Object> obj = Utils::OpenHandle(this);
   return obj->IsJSRegExp();
 }
 
 
 bool Value::IsGeneratorFunction() const {
@@ skipping 5851 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