[dwds] Cleanup unused null safety related fields (#2660)

* [dwds] Cleanup unused and deprecated members

- Fields related to null safety modes.
- Deprecated method parameter `injectDebuggingSupportCode`.

Author: nshahan

dwds/CHANGELOG.md

@@ -1,8 +1,12 @@
-## 24.4.2-wip
+## 25.0.0-wip
 
 - Implemented hot restart over websockets with multi window support.
 - Fix refresh race condition bug by adding an isolate destruction grace period.
 - Update a call to the `package:shelf_web_socket` `webSocketHandler()` function.
+- Remove deprecated parameter `injectDebuggingSupportCode` from `Dwds.start()`.
+- Remove all deprecated fields, getters, and parameters
+  related to the null safety compilation mode. Dart 3 only
+  supports [sound null safety](https://dart.dev/null-safety).
 
 ## 24.4.1
 

dwds/lib/dart_web_debug_service.dart

@@ -74,11 +74,6 @@ class Dwds {
     required Stream<BuildResult> buildResults,
     required ConnectionProvider chromeConnection,
     required ToolConfiguration toolConfiguration,
-    // ignore: avoid-unused-parameters
-    @Deprecated(
-      'This parameter is ignored and will be removed in a future version.',
-    )
-    bool injectDebuggingSupportCode = true,
     bool useDwdsWebSocketConnection = false,
   }) async {
     globalToolConfiguration = toolConfiguration;