Fix pressing <Space> in content-editable windows. Closes issue #not-in-the-tracker-for-some-reason.

common/modules/styles.jsm

@@ -574,6 +574,7 @@ var Styles = Module("Styles", {
                 }
             },
             {
+                bang: true,
                 completer: function (context, args) {
                     let compl = [];
                     let sheet = args["-group"].get(args["-name"]);