A rule filter may be used to add additional filtering of results to a rule.
 The filter is used to further reject results from matching the template's
 rules, beyond what the template syntax can do itself, thus allowing for
 more complex result filtering. The rule filter is applied after the rule
 syntax within the template.

 Only one filter may apply to each rule within the template and may be
 assigned using the template builder's addRuleFilter method.
[scriptable, uuid(819cd1ed-8010-42e1-a8b9-778b726a1ff3)]
interface nsIXULTemplateRuleFilter : nsISupports

Methods

 Evaluate a result and return true if the result is accepted by this
 filter, or false if it is rejected. Accepted results will have output
 generated for them for the rule. Rejected results will not, but they
 may still match another rule.

 @param aRef the result to examine
 @param aRule the rule node

 @return true if the rule matches
boolean match(in nsIXULTemplateResult aRef, in nsIDOMNode aRule)