Disable jank metrics for web (#109356)

packages/flutter_tools/lib/src/base/command_help.dart

@@ -120,7 +120,7 @@ class CommandHelp {
 
   late final CommandHelpOption j = _makeOption(
     'j',
-    'Dump frame raster stats for the current frame.',
+    'Dump frame raster stats for the current frame. (Unsupported for web)',
   );
 
   late final CommandHelpOption k = _makeOption(

packages/flutter_tools/lib/src/resident_runner.dart

@@ -701,6 +701,10 @@ abstract class ResidentHandlers {
       return false;
     }
     for (final FlutterDevice? device in flutterDevices) {
+      if (device?.targetPlatform == TargetPlatform.web_javascript) {
+        logger!.printWarning('Unable to get jank metrics for web');
+        continue;
+      }
       final List<FlutterView> views = await device!.vmService!.getFlutterViews();
       for (final FlutterView view in views) {
         final Map<String, Object>? rasterData =

packages/flutter_tools/test/general.shard/terminal_handler_test.dart

@@ -177,6 +177,12 @@ void main() {
       await terminalHandler.processTerminalInput('a');
     });
 
+    testWithoutContext('j unsupported jank metrics for web', () async {
+      final TerminalHandler terminalHandler = setUpTerminalHandler(<FakeVmServiceRequest>[], web: true);
+      await terminalHandler.processTerminalInput('j');
+      expect(terminalHandler.logger.warningText.contains('Unable to get jank metrics for web'), true);
+    });
+
     testWithoutContext('a - debugToggleProfileWidgetBuilds without service protocol is skipped', () async {
       final TerminalHandler terminalHandler = setUpTerminalHandler(<FakeVmServiceRequest>[], supportsServiceProtocol: false);
 

packages/flutter_tools/test/integration.shard/overall_experience_test.dart

@@ -612,7 +612,7 @@ void main() {
       'a Toggle timeline events for all widget build methods.                    (debugProfileWidgetBuilds)',
       'M Write SkSL shaders to a unique file in the project directory.',
       'g Run source code generators.',
-      'j Dump frame raster stats for the current frame.',
+      'j Dump frame raster stats for the current frame. (Unsupported for web)',
       'h Repeat this help message.',
       'd Detach (terminate "flutter run" but leave application running).',
       'c Clear the screen',