ES6: Unscopable should use ToBoolean

src/contexts.cc

 // Copyright 2011 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/v8.h"
 
 #include "src/bootstrapper.h"
 #include "src/debug.h"
 #include "src/scopeinfo.h"
 
@@ skipping 123 matching lines @@
     return Nothing<PropertyAttributes>();
   }
   if (!unscopables->IsSpecObject()) return attrs;
   Handle<Object> blacklist;
   MaybeHandle<Object> maybe_blacklist =
       Object::GetProperty(unscopables, it->name());
   if (!maybe_blacklist.ToHandle(&blacklist)) {
     DCHECK(isolate->has_pending_exception());
     return Nothing<PropertyAttributes>();
   }
-  return blacklist->IsUndefined() ? attrs : Just(ABSENT);
+  return blacklist->BooleanValue() ? Just(ABSENT) : attrs;
 }
 
 static void GetAttributesAndBindingFlags(VariableMode mode,
                                          InitializationFlag init_flag,
                                          PropertyAttributes* attributes,
                                          BindingFlags* binding_flags) {
   switch (mode) {
     case INTERNAL:  // Fall through.
     case VAR:
       *attributes = NONE;
@@ skipping 333 matching lines @@
 bool Context::IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object) {
   // During bootstrapping we allow all objects to pass as global
   // objects. This is necessary to fix circular dependencies.
   return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
       isolate->bootstrapper()->IsActive() ||
       object->IsGlobalObject();
 }
 #endif
 
 } }  // namespace v8::internal