Reference to undefined method trackPostId

[jeffreyvr]

Hi,

The integrations reference to the trackPostId method (from class ABTestTracking) which no longer exists. If I look at the commit history, it appears it has been replaced by trackGoal.

I have seen this causing a fatal error on form submits with GravityForms. But the method is also used in other integrations, so I imagine the same issue there.

I would submit a pull request, but I'm not entirely sure if the only changing the method to trackGoal would fix since I am not familiar with what needs to be done when trackPostId is called.