Unship arrow functions

...until the hotfix has baked.

R=hablich@chromium.org
BUG=v8:4211
LOG=Y

Review URL: https://codereview.chromium.org/1310243002

Cr-Commit-Position: refs/heads/master@{#30332}

src/flag-definitions.h

@@ -204,6 +204,7 @@ DEFINE_BOOL(legacy_const, true, "legacy semantics for const in sloppy mode")
 
 // Features that are complete (but still behind --harmony/es-staging flag).
 #define HARMONY_STAGED(V)                                       \
+  V(harmony_arrow_functions, "harmony arrow functions")         \
   V(harmony_array_includes, "harmony Array.prototype.includes") \
   V(harmony_tostring, "harmony toString")                       \
   V(harmony_concat_spreadable, "harmony isConcatSpreadable")    \
@@ -212,7 +213,6 @@ DEFINE_BOOL(legacy_const, true, "legacy semantics for const in sloppy mode")
 
 // Features that are shipping (turned on by default, but internal flag remains).
 #define HARMONY_SHIPPING(V)                                    \
-  V(harmony_arrow_functions, "harmony arrow functions")        \
   V(harmony_new_target, "harmony new.target")                  \
   V(harmony_object_observe, "harmony Object.observe")          \
   V(harmony_spreadcalls, "harmony spread-calls")               \