fix analyzer issue

Author: goderbauer

lib/ui/platform_dispatcher.dart

@@ -2414,7 +2414,7 @@ class SemanticsActionEvent {
   /// Optional arguments for the action.
   final Object? arguments;
 
-  static const _noArgumentPlaceholder = Object();
+  static const Object _noArgumentPlaceholder = Object();
 
   /// Create a clone of the [SemanticsActionEvent] but with provided parameters
   /// replaced.

lib/web_ui/lib/platform_dispatcher.dart

@@ -513,7 +513,7 @@ class SemanticsActionEvent {
   final int nodeId;
   final Object? arguments;
 
-  static const _noArgumentPlaceholder = Object();
+  static const Object _noArgumentPlaceholder = Object();
 
   SemanticsActionEvent copyWith({
     SemanticsAction? type,

lib/web_ui/lib/src/engine/platform_dispatcher.dart

@@ -169,6 +169,7 @@ class EnginePlatformDispatcher extends ui.PlatformDispatcher {
 
   /// Returns the [FlutterView] with the provided ID if one exists, or null
   /// otherwise.
+  @override
   ui.FlutterView? view({required int id}) => viewData[id];
 
   /// A map of opaque platform window identifiers to window configurations.