Trim sitefilters.

common/modules/options.jsm

@@ -453,7 +453,7 @@ var Option = Class("Option", {
             result = undefined;
 
         let [, bang, filter] = /^(!?)(.*)/.exec(pattern);
-        filter = Option.dequote(filter);
+        filter = Option.dequote(filter).trim();
 
         let quote = this.keepQuotes ? util.identity : Option.quote;
 

common/modules/styles.jsm

@@ -420,6 +420,8 @@ var Styles = Module("Styles", {
      * @returns {nsIURI -> boolean}
      */
     matchFilter: function (filter) {
+        filter = filter.trim();
+
         if (filter === "*")
             var test = function test(uri) true;
         else if (!/^(?:[a-z-]+:|[a-z-.]+$)/.test(filter)) {