TF-2537 Fix app crash when user trying attach file to composer in web app

Signed-off-by: dab246 <tdvu@linagora.com>

core/lib/utils/platform_info.dart

@@ -1,6 +1,7 @@
 import 'dart:io';
 
 import 'package:core/utils/app_logger.dart';
+import 'package:core/utils/web_renderer/canvas_kit.dart';
 import 'package:flutter/foundation.dart';
 
 abstract class PlatformInfo {
@@ -13,7 +14,7 @@ abstract class PlatformInfo {
   static bool get isAndroid => !kIsWeb && Platform.isAndroid;
   static bool get isMobile => isAndroid || isIOS;
   static bool get isDesktop => isLinux || isWindows || isMacOS;
-  static bool get isWebMobile => kIsWeb && (defaultTargetPlatform == TargetPlatform.iOS || defaultTargetPlatform == TargetPlatform.android);
+  static bool get isCanvasKit => isRendererCanvasKit;
 
   static String get platformNameOS {
     var platformName = '';

core/lib/utils/web_renderer/canvas_kit.dart

@@ -0,0 +1 @@
+export 'canvas_kit_stub.dart' if (dart.library.html) 'canvas_kit_web.dart';

core/lib/utils/web_renderer/canvas_kit_stub.dart

@@ -0,0 +1,4 @@
+/// Whether the CanvasKit renderer is being used on web.
+///
+/// Always returns `false` on non-web.
+bool get isRendererCanvasKit => false;

core/lib/utils/web_renderer/canvas_kit_web.dart

@@ -0,0 +1,6 @@
+import 'dart:js' as js;
+
+/// Whether the CanvasKit renderer is being used on web.
+///
+/// Always returns `false` on non-web.
+bool get isRendererCanvasKit => js.context['flutterCanvasKit'] != null;