2502 [e2e] e2e web changes part1: registering web extension. (cla: yes)

2504 [in_app_purchase] Fix wrong _pendingCompletePurchase flag value (cla: yes)

2505 [google_maps_flutter] getZoomLevel for map controller (cla: yes, submit queue)

2507 [google_maps_flutter] Add steps to set up google map sdk on each platform in readme. (cla: yes)

2508 [google_sign_in_web] Add more detailed setup instructions. (cla: yes)

2509 [in_app_purchases] Android: make sure properly disconnect the billing client object. (cla: yes)

2514 [e2e] Test multiple failure behavior (cla: yes)

2515 [Connectivity] Adds platform interface to connectivity plugin (cla: yes)