Allen Wirfs-Brock (2014-02-18T18:54:41.000Z)
domenic at domenicdenicola.com (2014-02-24T21:07:49.279Z)
No, even if you removed the checks in Map and Promise and WeakMap that prevent them from trying to initialize an object that lacks the appropriate internal slots it still wouldn't work because obj does not have the internal slots necessary to support the built-in operations upon those objects and implementations commonly implement such objects in a manner that prevents the dynamic addition of such slots. The whole purpose of @@create is to allow implementations to allocate prior to invoking a constructor the correctly shaped object for built-ins.