[Core] Flutter Firebase app not compilable anymore :(

[Ahmadre]

Describe the bug
Can't run and build a native flutter ios or android app

To Reproduce
Steps to reproduce the behavior:

1. Be on firebase_core-0.4.4+2
2. try 'flutter run'

Expected behavior
Flutter runs and builds

Additional context

Crash-Report

Launching lib/main.dart on iPhone 11 Pro Max in debug mode...
Xcode build done.                                           84,3s
Failed to build iOS app
Error output from Xcode build:
↳
    ** BUILD FAILED **
Xcode's output:
↳
    /Users/rebar/.pub-cache/hosted/pub.dartlang.org/firebase_core-0.4.4+2/darwin/Classes/FLTFirebaseCorePlugin.m:6:9: fatal error: 'UserAgent.h' file not found
    #import "UserAgent.h"
            ^~~~~~~~~~~~~
    1 error generated.
Could not build the application for the simulator.
Error launching application on iPhone 11 Pro Max.
Exited (sigterm)

maybe related to this PR: #2099

[iapicca]

Hi @Ahmadre
I see there's an open issue addressing the case you described.
Please follow up on that issue,
I'm closing the current one as duplicate.
If you disagree please write in the comments
and I will reopen it.
Thank you