Ship ES6 computed property names

BUG=v8:3754
LOG=N
R=dslomov@chromium.org, rossberg@chromium.org

Review URL: https://codereview.chromium.org/1054883003

Cr-Commit-Position: refs/heads/master@{#27676}

src/flag-definitions.h

@@ -196,13 +196,13 @@ DEFINE_IMPLICATION(es_staging, harmony)
 
 // Features that are complete (but still behind --harmony/es-staging flag).
 #define HARMONY_STAGED(V)                                               \
-  V(harmony_computed_property_names, "harmony computed property names") \
   V(harmony_tostring, "harmony toString")                               \
   V(harmony_unicode, "harmony unicode escapes")
 
 // Features that are shipping (turned on by default, but internal flag remains).
 #define HARMONY_SHIPPING(V)                                                \
   V(harmony_classes, "harmony classes (implies object literal extension)") \
+  V(harmony_computed_property_names, "harmony computed property names")    \
   V(harmony_object_literals, "harmony object literal extensions")
 
 // Once a shipping feature has proved stable in the wild, it will be dropped