Reland "[es6] Fix Function and GeneratorFunction built-ins subclassing."

src/objects-printer.cc

Index: src/objects-printer.cc
diff --git a/src/objects-printer.cc b/src/objects-printer.cc
index efc97a4766ef009a8f62d0333a3c4fb3a86f8bee..5ecafe2a00a06ea21b8195303d25efe3b033f3b2 100644
--- a/src/objects-printer.cc
+++ b/src/objects-printer.cc
@@ -867,6 +867,9 @@ void JSFunction::JSFunctionPrint(std::ostream& os) {  // NOLINT
   if (has_initial_map()) os << Brief(initial_map());
   os << "\n - shared_info = " << Brief(shared());
   os << "\n   - name = " << Brief(shared()->name());
+  if (shared()->is_generator()) {
+    os << "\n   - generator";
+  }
   os << "\n - context = " << Brief(context());
   if (shared()->bound()) {
     os << "\n - bindings = " << Brief(function_bindings());