Fix a null error for _defaultAction in ChromeTabs.

omega-target-chromium-extension/src/tabs.coffee

@@ -40,6 +40,7 @@ class ChromeTabs
         try chrome.browserAction.setBadgeText(text: '', tabId: id)
         @_badgeTab = null
     if not tab.url? or tab.url.indexOf("chrome") == 0
+      if @_defaultAction
         chrome.browserAction.setTitle(title: @_defaultAction.title, tabId: tab.id)
         @clearIcon tab.id
       return