Stage --harmony-function-tostring

BUG=v8:4958

Change-Id: Id02d36fce76eed54a5a3d348dbac2ea7d43f4ef3
Reviewed-on: https://chromium-review.googlesource.com/462336Reviewed-by: Daniel Ehrenberg <littledan@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44275}

src/flag-definitions.h

@@ -206,7 +206,6 @@ DEFINE_IMPLICATION(es_staging, move_object_start)
   V(harmony_do_expressions, "harmony do-expressions")                   \
   V(harmony_regexp_named_captures, "harmony regexp named captures")     \
   V(harmony_regexp_property, "harmony unicode regexp property classes") \
-  V(harmony_function_tostring, "harmony Function.prototype.toString")   \
   V(harmony_class_fields, "harmony public fields in class literals")    \
   V(harmony_async_iteration, "harmony async iteration")                 \
   V(harmony_dynamic_import, "harmony dynamic import")                   \
@@ -214,6 +213,7 @@ DEFINE_IMPLICATION(es_staging, move_object_start)
 
 // Features that are complete (but still behind --harmony/es-staging flag).
 #define HARMONY_STAGED(V)                                                \
+  V(harmony_function_tostring, "harmony Function.prototype.toString")    \
   V(harmony_regexp_lookbehind, "harmony regexp lookbehind")              \
   V(harmony_restrictive_generators,                                      \
     "harmony restrictions on generator declarations")                    \

test/mjsunit/messages.js

@@ -371,7 +371,7 @@ test(function() {
 // kParenthesisInArgString
 test(function() {
   new Function(")", "");
-}, "Function arg string contains parenthesis", SyntaxError);
+}, "Arg string terminates parameters early", SyntaxError);
 
 // === ReferenceError ===