fix: Remove dart:io imports for analytics, auth and app check (#16827)

Allows these packages to be detected as wasm-compatible

Packages:
- firebase_analytics
- firebase_app_check
- firebase_auth

Co-authored-by: Russell Wheatley <russellwheatley85@gmail.com>

packages/firebase_analytics/firebase_analytics_platform_interface/lib/src/method_channel/method_channel_firebase_analytics.dart

@@ -3,10 +3,10 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:io';
 
 import 'package:firebase_analytics_platform_interface/firebase_analytics_platform_interface.dart';
 import 'package:firebase_core/firebase_core.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 
 import 'utils/exception.dart';
@@ -202,7 +202,7 @@ class MethodChannelFirebaseAnalytics extends FirebaseAnalyticsPlatform {
   @override
   Future<void> setSessionTimeoutDuration(Duration timeout) async {
     try {
-      if (Platform.isAndroid) {
+      if (!kIsWeb && defaultTargetPlatform == TargetPlatform.android) {
         return channel.invokeMethod<void>(
             'Analytics#setSessionTimeoutDuration', <String, int>{
           'milliseconds': timeout.inMilliseconds,

packages/firebase_app_check/firebase_app_check_platform_interface/lib/src/method_channel/method_channel_firebase_app_check.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:io';
 
 import 'package:_flutterfire_internals/_flutterfire_internals.dart';
 import 'package:firebase_core/firebase_core.dart';
@@ -84,9 +83,11 @@ class MethodChannelFirebaseAppCheck extends FirebaseAppCheckPlatform {
       await channel.invokeMethod<void>('FirebaseAppCheck#activate', {
         'appName': app.name,
         // Allow value to pass for debug mode for unit testing
-        if (Platform.isAndroid || kDebugMode)
+        if (defaultTargetPlatform == TargetPlatform.android || kDebugMode)
           'androidProvider': getAndroidProviderString(androidProvider),
-        if (Platform.isIOS || Platform.isMacOS || kDebugMode)
+        if (defaultTargetPlatform == TargetPlatform.iOS ||
+            defaultTargetPlatform == TargetPlatform.macOS ||
+            kDebugMode)
           'appleProvider': getAppleProviderString(appleProvider),
       });
     } on PlatformException catch (e, s) {

packages/firebase_auth/firebase_auth/lib/firebase_auth.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:io';
 
 import 'package:firebase_auth_platform_interface/firebase_auth_platform_interface.dart';
 import 'package:firebase_core/firebase_core.dart';

packages/firebase_auth/firebase_auth/lib/src/user.dart

@@ -673,7 +673,9 @@ class User {
   }
 
   MultiFactor get multiFactor {
-    if (!kIsWeb && (Platform.isMacOS || Platform.isWindows)) {
+    if (!kIsWeb &&
+        (defaultTargetPlatform == TargetPlatform.macOS ||
+            defaultTargetPlatform == TargetPlatform.windows)) {
       throw UnimplementedError(
         'MultiFactor Authentication is only supported on web, Android and iOS.',
       );