Enable --harmony-trailing-commas

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 2da3918a52a4bc4f1c5c96ab3c928d9f544a2cb6..eb5027a329acd1348552e9ce8e77f5e45482ad4f 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -211,12 +211,12 @@ DEFINE_IMPLICATION(es_staging, move_object_start)
   V(harmony_restrictive_generators,                         \
     "harmony restrictions on generator declarations")       \
   V(harmony_tailcalls, "harmony tail calls")                \
-  V(harmony_trailing_commas,                                \
-    "harmony trailing commas in function parameter lists")  \
   V(harmony_object_rest_spread, "harmony object rest spread properties")
 
 // Features that are shipping (turned on by default, but internal flag remains).
-#define HARMONY_SHIPPING_BASE(V)
+#define HARMONY_SHIPPING_BASE(V) \
+  V(harmony_trailing_commas,     \
+    "harmony trailing commas in function parameter lists")
 
 #ifdef V8_I18N_SUPPORT
 #define HARMONY_SHIPPING(V)                                        \