Remove Object::IsSpecObject, use Object::IsJSReceiver instead.

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index c0062c52f2b8d467ffa8c763678b73e5388908cf..d7824504cae7b1a5c4d780914732a8728997bf7d 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -1189,7 +1189,7 @@ bool HasConcatSpreadableModifier(Isolate* isolate, Handle<JSArray> obj) {
 
 bool IsConcatSpreadable(Isolate* isolate, Handle<Object> obj) {
   HandleScope handle_scope(isolate);
-  if (!obj->IsSpecObject()) return false;
+  if (!obj->IsJSReceiver()) return false;
   if (FLAG_harmony_concat_spreadable) {
     Handle<Symbol> key(isolate->factory()->is_concat_spreadable_symbol());
     Handle<Object> value;