initialize menuhandle to null; r=sfraser; bug #45245

widget/src/mac/nsMenuBar.cpp

@@ -386,7 +386,7 @@ nsMenuBar::MenuConstruct( const nsMenuEvent & aMenuEvent, nsIWidget* aParentWind
           menuElement->GetAttribute(NS_ConvertASCIItoUCS2("id"), menuIDstring);
           if(menuIDstring.EqualsWithConversion("menu_Help")) {
             nsMenuEvent event;
-            MenuHandle handle;
+            MenuHandle handle = nsnull;
 #if !(defined(RHAPSODY) || defined(TARGET_CARBON))
             ::HMGetHelpMenuHandle(&handle);
 #endif