Do not use js builtins object to determine whether a function is a builtin.

src/debug/debug-scopes.cc

 // Copyright 2015 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/debug/debug-scopes.h"
 
 #include "src/debug/debug.h"
 #include "src/frames-inl.h"
 #include "src/globals.h"
 #include "src/parser.h"
@@ skipping 100 matching lines @@
   }
 }
 
 
 ScopeIterator::ScopeIterator(Isolate* isolate, Handle<JSFunction> function)
     : isolate_(isolate),
       frame_inspector_(NULL),
       context_(function->context()),
       seen_script_scope_(false),
       failed_(false) {
-  if (function->IsBuiltin()) context_ = Handle<Context>();
+  if (!function->IsSubjectToDebugging()) context_ = Handle<Context>();
 }
 
 
 MUST_USE_RESULT MaybeHandle<JSObject> ScopeIterator::MaterializeScopeDetails() {
   // Calculate the size of the result.
   Handle<FixedArray> details =
       isolate_->factory()->NewFixedArray(kScopeDetailsSize);
   // Fill in scope details.
   details->set(kScopeDetailsTypeIndex, Smi::FromInt(Type()));
   Handle<JSObject> scope_object;
@@ skipping 628 matching lines @@
     // TODO(verwaest): Use AddDataProperty instead.
     JSObject::SetOwnPropertyIgnoreAttributes(
         scope_object, handle(String::cast(scope_info->get(i + start))), value,
         ::NONE)
         .Check();
   }
 }
 
 }  // namespace internal
 }  // namespace v8