use brand name in Quit menu item title on Macs (this localization is only used by Cocoa widget builds currently, Carbon makes up its own title). b=333879 r=mconnor

browser/locales/en-US/chrome/browser/browser.dtd

@@ -327,7 +327,7 @@
 <!ENTITY goForwardCmd.commandKey "]">
 <!ENTITY quitApplicationCmd.label       "Quit"> 
 <!ENTITY quitApplicationCmd.accesskey   "Q">
-<!ENTITY quitApplicationCmdMac.label    "Quit">
+<!ENTITY quitApplicationCmdMac.label    "Quit &brandShortName;">
 <!ENTITY quitApplicationCmdMac.key      "Q">
 
 <!ENTITY closeCmd.label                 "Close">