[es6] Initial steps towards a correct implementation of IsCallable.

src/runtime/runtime-classes.cc

 // Copyright 2014 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/runtime/runtime-utils.h"
 
 #include <stdlib.h>
 #include <limits>
 
 #include "src/arguments.h"
@@ skipping 86 matching lines @@
                                        Handle<JSFunction> constructor,
                                        int start_position, int end_position) {
   Handle<Object> prototype_parent;
   Handle<Object> constructor_parent;
 
   if (super_class->IsTheHole()) {
     prototype_parent = isolate->initial_object_prototype();
   } else {
     if (super_class->IsNull()) {
       prototype_parent = isolate->factory()->null_value();
-    } else if (super_class->IsSpecFunction()) {
+    } else if (super_class->IsJSFunction()) {

[rossberg, 2015/08/26 12:55:48]

Shouldn't this be IsCallable as well? It's perfectly legal to inherit from, say,
a function proxy.

[Benedikt Meurer, 2015/08/27 05:18:23]

Actually it should be IsConstructor, but we don't have that yet. Plus there's a
JSFunction cast on the next line. So I'll add a TODO and clean it up later once
we have proper IsConstructor.

       if (Handle<JSFunction>::cast(super_class)->shared()->is_generator()) {
         THROW_NEW_ERROR(
             isolate,
             NewTypeError(MessageTemplate::kExtendsValueGenerator, super_class),
             Object);
       }
       ASSIGN_RETURN_ON_EXCEPTION(
           isolate, prototype_parent,
           Runtime::GetObjectProperty(isolate, super_class,
                                      isolate->factory()->prototype_string(),
@@ skipping 445 matching lines @@
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, result,
       Execution::Call(isolate, reflect, isolate->factory()->undefined_value(),
                       arraysize(argv), argv));
 
   return *result;
 }
 }  // namespace internal
 }  // namespace v8