Enumeration order needs to be correctly implemented

[IgnoredAmbience]

ordinary_own_property_keys needs a correct implementation.

The main hurdle here is the chronological ordering of steps 3 and 4:

3. For each own property key P of O that is a String but is not an integer index, in ascending chronological order of property creation, do
4. For each own property key P of O that is a Symbol, in ascending chronological order of property creation, do

Following this, an implementation of the for-in enumeration order defined by EnumerateObjectProperties is required.

Then, enumerable_own_properties can also be implemented.

[IgnoredAmbience]

For-in reform is being discussed in tc39/ecma262#1281, https://github.com/bakkot/for-in-exploration and at the next tc39 meeting: https://docs.google.com/presentation/d/1ppVLFjnd2iGksBXeu97lml2cs9dTRJnJLfufcshvPcs/edit?usp=sharing

[brabalan]

This is great news. I won't be at the September meeting but I'll try to learn more at the November's one.

[IgnoredAmbience]

I may dial into the September one to listen in on the discussion.