Verify that Api function's instance call handler is actually a CallHandlerInfo structure.

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index b8d0b42d50e8f757497c12696d5112b1d03043b8..b8a10efe6e110ae2f9d7a4f59d2cca58fc992201 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -1118,6 +1118,8 @@ MUST_USE_RESULT static Object* HandleApiCallHelper(
 
   Object* raw_call_data = fun_data->call_code();
   if (!raw_call_data->IsUndefined()) {
+    // TODO(ishell): remove this debugging code.
+    CHECK(raw_call_data->IsCallHandlerInfo());
     CallHandlerInfo* call_data = CallHandlerInfo::cast(raw_call_data);
     Object* callback_obj = call_data->callback();
     v8::FunctionCallback callback =
@@ -1187,6 +1189,8 @@ MUST_USE_RESULT static Object* HandleApiCallAsFunctionOrConstructor(
   Object* handler =
       constructor->shared()->get_api_func_data()->instance_call_handler();
   DCHECK(!handler->IsUndefined());
+  // TODO(ishell): remove this debugging code.
+  CHECK(handler->IsCallHandlerInfo());
   CallHandlerInfo* call_data = CallHandlerInfo::cast(handler);
   Object* callback_obj = call_data->callback();
   v8::FunctionCallback callback =