Make CallSite constructor inaccessible from JS

src/builtins/builtins-internal.cc

Index: src/builtins/builtins-internal.cc
diff --git a/src/builtins/builtins-internal.cc b/src/builtins/builtins-internal.cc
index 2ac2454e4c9b5b561f87d4763c98cfca09894240..82ff1534ebaec7e22a7a86eb369d9777781d94e2 100644
--- a/src/builtins/builtins-internal.cc
+++ b/src/builtins/builtins-internal.cc
@@ -17,6 +17,12 @@ BUILTIN(Illegal) {
 
 BUILTIN(EmptyFunction) { return isolate->heap()->undefined_value(); }
 
+BUILTIN(UnsupportedThrower) {
+  HandleScope scope(isolate);
+  THROW_NEW_ERROR_RETURN_FAILURE(isolate,
+                                 NewError(MessageTemplate::kUnsupported));
+}
+
 // -----------------------------------------------------------------------------
 // Throwers for restricted function properties and strict arguments object
 // properties