Fix bug 415253 - Reload causes error in hidden Unifinder [Error: unifinderTreeView.clearEvents is not a function] (regression)

calendar/base/content/calendar-unifinder.js

@@ -115,7 +115,7 @@ var unifinderObserver = {
             // those operations and refresh as soon as the unifinder is shown
             // again.
             gUnifinderNeedsRefresh = true;
-            unifinderTreeView.clearEvents();
+            unifinderTreeView.clearItems();
         }
         if (!this.mInBatch) {
             refreshEventTree();