[ Tool ] Output DTD URI for Flutter web applications (flutter#177310)

Fixes flutter#176310

Author: bkonyi

packages/flutter_tools/lib/src/isolated/resident_web_runner.dart

@@ -934,7 +934,7 @@ class ResidentWebRunner extends ResidentRunner {
             DebugConnectionInfo(
               wsUri: websocketUri,
               devToolsUri: Uri.tryParse(debugConnection.devToolsUri ?? ''),
-              // TODO(bkonyi): surface DTD URI once it's visible from DWDS
+              dtdUri: Uri.tryParse(debugConnection.dtdUri ?? ''),
             ),
           );
         }),

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

@@ -144,6 +144,7 @@ name: my_app
     webDevFS.result = ConnectionResult(appConnection, debugConnection, debugConnection.vmService);
     debugConnection.uri = 'ws://127.0.0.1/abcd/';
     debugConnection.devToolsUri = 'http://127.0.0.1/abcd/';
+    debugConnection.dtdUri = 'ws://127.0.0.1/efgh/';
     chromeConnection.tabs.add(chromeTab);
   }
 
@@ -260,6 +261,7 @@ name: my_app
       expect(appConnection.ranMain, true);
       expect(logger.statusText, contains('Debug service listening on ws://127.0.0.1/abcd/'));
       expect(debugConnectionInfo.wsUri.toString(), 'ws://127.0.0.1/abcd/');
+      expect(debugConnectionInfo.dtdUri.toString(), 'ws://127.0.0.1/efgh/');
     },
     overrides: <Type, Generator>{
       FileSystem: () => fileSystem,
@@ -2029,6 +2031,9 @@ class FakeDebugConnection extends Fake implements DebugConnection {
   @override
   late String devToolsUri;
 
+  @override
+  late String dtdUri;
+
   final completer = Completer<void>();
   var didClose = false;