title: "Cannot find name 'serviceworkerregistration'" when using firebase >= 5.0.1 in cloud functions
body: <p>I have some shared typescript code between my Ionic app and cloud functions in a separate nodejs package which includes some models, utils, ... Now, I also use some classes of firebase firestore in it like GeoPoint and Timestamp. When I use firebase package 5.0.1 or above I got an exception like "cannot find name 'serviceworkerregistration'" when I want to build my cloud functions project.
  Any idea on whats the best way to deal with some shared code which includes firestore logic?</p>