Allowed link targets button config not being passed to ButtonTargetList

[mattleff]

With the following configuration the link targets should be limited:

AlloyEditor.editable(element, {
  buttonCfg: {
    'linkEdit': {
      allowedTargets: [
        {
          label: AlloyEditor.Strings.linkTargetDefault,
          value: ''
        }, {
          label: AlloyEditor.Strings.linkTargetBlank,
          value: '_blank'
        }
      ]
    }
  }
});

This was working and seems to have been broken with 7858e3b. #572 is the fix.