ES6: Update unscopables to match spec

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 116 matching lines @@
 
   Handle<Symbol> unscopables_symbol = isolate->factory()->unscopables_symbol();
   Handle<Object> receiver = it->GetReceiver();
   Handle<Object> unscopables;
   MaybeHandle<Object> maybe_unscopables =
       Object::GetProperty(receiver, unscopables_symbol);
   if (!maybe_unscopables.ToHandle(&unscopables)) {
     return Maybe<PropertyAttributes>();
   }
   if (!unscopables->IsSpecObject()) return attrs;
-  Maybe<bool> blacklist = JSReceiver::HasProperty(
-      Handle<JSReceiver>::cast(unscopables), it->name());
-  if (!blacklist.has_value) {
+  Handle<Object> blacklist;
+  MaybeHandle<Object> maybe_blacklist =
+      Object::GetProperty(unscopables, it->name());
+  if (!maybe_blacklist.ToHandle(&blacklist)) {
     DCHECK(isolate->has_pending_exception());
     return Maybe<PropertyAttributes>();
   }
-  if (blacklist.value) return maybe(ABSENT);
+  if (!blacklist->IsUndefined()) return maybe(ABSENT);
   return attrs;
 }
 
 static void GetAttributesAndBindingFlags(VariableMode mode,
                                          InitializationFlag init_flag,
                                          PropertyAttributes* attributes,
                                          BindingFlags* binding_flags) {
   switch (mode) {
     case INTERNAL:  // Fall through.
     case VAR:
@@ skipping 334 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