Normative: Require sorted output from AvailableCalendars

Author: gibson042

spec/calendar.html

@@ -62,6 +62,7 @@ <h1>
         1. Let _calendars_ be the List of String values representing calendar types supported by the implementation.
         1. Assert: _calendars_ contains *"iso8601"*.
         1. Assert: _calendars_ does not contain any element that does not identify a calendar type in the <a href="https://cldr.unicode.org/">Unicode Common Locale Data Repository (CLDR)</a>.
+        1. Sort _calendars_ in order as if an Array of the same values had been sorted using %Array.prototype.sort% with *undefined* as _comparefn_.
         1. Return _calendars_.
       </emu-alg>
     </emu-clause>