Adding the popup set atom to the XUL atom list.

content/shared/public/nsXULAtomList.h

@@ -72,6 +72,7 @@ XUL_ATOM(menupopup, "menupopup") // The XP menu's children.
 XUL_ATOM(menuactive, "menuactive") // Whether or not a menu is active (without necessarily being open)
 XUL_ATOM(accesskey, "accesskey") // The shortcut key for a menu or menu item
 XUL_ATOM(acceltext, "acceltext") // Text to use for the accelerator
+XUL_ATOM(menupopupset, "menupopupset") // Contains popup menus, context menus, and tooltips
 
 XUL_ATOM(key, "key") // A key element
 XUL_ATOM(broadcaster, "broadcaster") // A broadcaster

layout/xul/content/src/nsXULAtomList.h

@@ -72,6 +72,7 @@ XUL_ATOM(menupopup, "menupopup") // The XP menu's children.
 XUL_ATOM(menuactive, "menuactive") // Whether or not a menu is active (without necessarily being open)
 XUL_ATOM(accesskey, "accesskey") // The shortcut key for a menu or menu item
 XUL_ATOM(acceltext, "acceltext") // Text to use for the accelerator
+XUL_ATOM(menupopupset, "menupopupset") // Contains popup menus, context menus, and tooltips
 
 XUL_ATOM(key, "key") // A key element
 XUL_ATOM(broadcaster, "broadcaster") // A broadcaster