Add some runtime checks to MayNamedAccess

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 906 matching lines @@
   if (key == heap_.hidden_symbol()) return true;
 
   // Check for compatibility between the security tokens in the
   // current lexical context and the accessed object.
   ASSERT(context());
 
   MayAccessDecision decision = MayAccessPreCheck(this, receiver, type);
   if (decision != UNKNOWN) return decision == YES;
 
   // Get named access check callback
-  JSFunction* constructor = JSFunction::cast(receiver->map()->constructor());
+  // TODO(dcarney): revert
+  Map* map = receiver->map();
+  CHECK(map->IsMap());
+  CHECK(map->constructor()->IsJSFunction());
+  JSFunction* constructor = JSFunction::cast(map->constructor());
   if (!constructor->shared()->IsApiFunction()) return false;
 
   Object* data_obj =
      constructor->shared()->get_api_func_data()->access_check_info();
   if (data_obj == heap_.undefined_value()) return false;
 
   Object* fun_obj = AccessCheckInfo::cast(data_obj)->named_callback();
   v8::NamedSecurityCallback callback =
       v8::ToCData<v8::NamedSecurityCallback>(fun_obj);
 
@@ skipping 1274 matching lines @@
 
 #ifdef DEBUG
 #define ISOLATE_FIELD_OFFSET(type, name, ignored)                       \
 const intptr_t Isolate::name##_debug_offset_ = OFFSET_OF(Isolate, name##_);
 ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
 ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
 #undef ISOLATE_FIELD_OFFSET
 #endif
 
 } }  // namespace v8::internal