Bug 530533: Add pref to control whether addEngine prompts to "use immediately", r=rflint

toolkit/components/search/nsSearchService.js

@@ -1219,7 +1219,10 @@ Engine.prototype = {
     var dialogMessage =
         stringBundle.formatStringFromName("addEngineConfirmation",
                                           [this._name, this._uri.host], 2);
-    var checkboxMessage = stringBundle.GetStringFromName("addEngineUseNowText");
+    var checkboxMessage = null;
+    if (!getBoolPref(BROWSER_SEARCH_PREF + "noCurrentEngine", false))
+      checkboxMessage = stringBundle.GetStringFromName("addEngineUseNowText");
+
     var addButtonLabel =
         stringBundle.GetStringFromName("addEngineAddButtonLabel");