Don't unmark dictionary mode maps as unstable.

R=ulan@chromium.org
BUG=

Review URL: https://codereview.chromium.org/148493007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18983 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects-inl.h

@@ -3988,8 +3988,9 @@ bool Map::is_shared() {
 
 
 void Map::set_dictionary_map(bool value) {
-  if (value) mark_unstable();
-  set_bit_field3(DictionaryMap::update(bit_field3(), value));
+  uint32_t new_bit_field3 = DictionaryMap::update(bit_field3(), value);
+  new_bit_field3 = IsUnstable::update(new_bit_field3, value);
+  set_bit_field3(new_bit_field3);
 }
 
 

src/objects.cc

@@ -6682,7 +6682,9 @@ MaybeObject* Map::RawCopy(int instance_size) {
   new_bit_field3 = EnumLengthBits::update(new_bit_field3,
                                           kInvalidEnumCacheSentinel);
   new_bit_field3 = Deprecated::update(new_bit_field3, false);
-  new_bit_field3 = IsUnstable::update(new_bit_field3, false);
+  if (!is_dictionary_map()) {
+    new_bit_field3 = IsUnstable::update(new_bit_field3, false);
+  }
   result->set_bit_field3(new_bit_field3);
   return result;
 }