Fix DCM analyzer warnings (#2094)

Author: elliette

dwds/lib/src/debugging/debugger.dart

@@ -976,7 +976,7 @@ class _Breakpoints extends Domain {
   }
 
   /// Calls the Chrome protocol setBreakpoint and returns the remote ID.
-  Future<String?> _setJsBreakpoint(Location location) async {
+  Future<String?> _setJsBreakpoint(Location location) {
     // The module can be loaded from a nested path and contain an ETAG suffix.
     final urlRegex = '.*${location.jsLocation.module}.*';
     // Prevent `Aww, snap!` errors when setting multiple breakpoints

dwds/lib/src/debugging/frame_computer.dart

@@ -34,7 +34,7 @@ class FrameComputer {
 
   /// Translates Chrome callFrames contained in [DebuggerPausedEvent] into Dart
   /// [Frame]s.
-  Future<List<Frame>> calculateFrames({int? limit}) async {
+  Future<List<Frame>> calculateFrames({int? limit}) {
     return _queue.run(() async {
       if (limit != null && _computedFrames.length >= limit) {
         return _computedFrames.take(limit).toList();

dwds/lib/src/debugging/inspector.dart

@@ -577,7 +577,7 @@ class AppInspector implements AppInspectorInterface {
   /// reload the inspector will get re-created.
   ///
   /// Returns the list of scripts refs cached.
-  Future<List<ScriptRef>> _populateScriptCaches() async {
+  Future<List<ScriptRef>> _populateScriptCaches() {
     return _scriptCacheMemoizer.runOnce(() async {
       final scripts = await globalLoadStrategy
           .metadataProviderFor(appConnection.request.entrypointPath)

dwds/lib/src/handlers/dev_handler.dart

@@ -537,14 +537,14 @@ class DevHandler {
 
     while (await extensionBackend.connections.hasNext) {
       final extensionDebugger = await extensionBackend.extensionDebugger;
-      await _startExtensionDebugService(extensionDebugger);
+      _startExtensionDebugService(extensionDebugger);
     }
   }
 
   /// Starts a [DebugService] for Dart Debug Extension.
-  Future<void> _startExtensionDebugService(
+  void _startExtensionDebugService(
     ExtensionDebugger extensionDebugger,
-  ) async {
+  ) {
     // Waits for a `DevToolsRequest` to be sent from the extension background
     // when the extension is clicked.
     extensionDebugger.devToolsRequestStream.listen((devToolsRequest) async {