When calling menu item's click callback, pass the item object.

browser/api/lib/menu-item.coffee

@@ -20,9 +20,9 @@ class MenuItem
     throw new Error('Unknown menu type') if MenuItem.types.indexOf(@type) is -1
 
     @commandId = ++nextCommandId
-    @click = ->
+    @click = =>
       if typeof click is 'function'
-        click()
+        click.apply this, arguments
       else if typeof selector is 'string'
         Menu.sendActionToFirstResponder selector
 

browser/api/lib/menu.coffee

@@ -37,7 +37,9 @@ Menu::insert = (pos, item) ->
       isCommandIdEnabled: (commandId) => @commandsMap[commandId]?.enabled
       isCommandIdVisible: (commandId) => @commandsMap[commandId]?.visible
       getAcceleratorForCommandId: (commandId) => @commandsMap[commandId]?.accelerator
-      executeCommand: (commandId) => @commandsMap[commandId]?.click()
+      executeCommand: (commandId) =>
+        activeItem = @commandsMap[commandId]
+        activeItem.click(activeItem) if activeItem?
   @items.splice pos, 0, item
   @commandsMap[item.commandId] = item