mapcss regular expression matches for key

[maxerickson@…]

Between 14460 and 14469, regular expressions for keys in the validator stopped working. Given simple data like (the only part used for the example tests is "name=Test St"):

<?xml version='1.0' encoding='UTF-8'?>
<osm version='0.6' generator='JOSM'>
  <node id='-160658' action='modify' visible='true' lat='25.49069474072' lon='-80.4196570082' />
  <node id='-160660' action='modify' visible='true' lat='25.4906898985' lon='-80.41959934071' />
  <way id='-160661' action='modify' visible='true'>
    <nd ref='-160658' />
    <nd ref='-160660' />
    <tag k='highway' v='residential' />
    <tag k='name' v='Test St' />
  </way>
</osm>

A selector like [/^name/] has stopped working:

*[name=~/Test/]{
  throwWarning: "Value match";
}

*[/name/=~/Test/]{
  throwWarning: "Simple key value match.";
}

*[/^name/=~/Test/]{
  throwWarning: "Key value match";
}

In 14460, the "Key value match" test warns, in 14469 it does not. The other 2 work in both.

Probably related to the work on #17021.