[ci] Enable LUCI Dart unit tests (#4378)

Enables the new LUCI Dart unit tests.

There is no corresponding Cirrus removal because that test was
accidentally removed early in
https://github.com/flutter/packages/pull/4352.

Part of https://github.com/flutter/flutter/issues/114373

.ci.yaml

@@ -93,10 +93,10 @@ targets:
       version_file: flutter_master.version
 
   - name: Linux dart_unit_test_shard_1 master
-    bringup: true # New target
     recipe: packages/packages
     timeout: 60
     properties:
+      add_recipes_cq: "true"
       target_file: dart_unit_tests.yaml
       channel: master
       version_file: flutter_master.version
@@ -104,10 +104,10 @@ targets:
       package_sharding: "--shardIndex 0 --shardCount 2"
 
   - name: Linux dart_unit_test_shard_2 master
-    bringup: true # New target
     recipe: packages/packages
     timeout: 60
     properties:
+      add_recipes_cq: "true"
       target_file: dart_unit_tests.yaml
       channel: master
       version_file: flutter_master.version
@@ -115,7 +115,6 @@ targets:
       package_sharding: "--shardIndex 1 --shardCount 2"
 
   - name: Linux dart_unit_test_shard_1 stable
-    bringup: true # New target
     recipe: packages/packages
     timeout: 60
     properties:
@@ -126,7 +125,6 @@ targets:
       package_sharding: "--shardIndex 0 --shardCount 2"
 
   - name: Linux dart_unit_test_shard_2 stable
-    bringup: true # New target
     recipe: packages/packages
     timeout: 60
     properties:
@@ -137,10 +135,10 @@ targets:
       package_sharding: "--shardIndex 1 --shardCount 2"
 
   - name: Linux_web web_dart_unit_test_shard_1 master
-    bringup: true # New target
     recipe: packages/packages
     timeout: 60
     properties:
+      add_recipes_cq: "true"
       target_file: web_dart_unit_tests.yaml
       channel: master
       version_file: flutter_master.version
@@ -148,10 +146,10 @@ targets:
       package_sharding: "--shardIndex 0 --shardCount 2"
 
   - name: Linux_web web_dart_unit_test_shard_2 master
-    bringup: true # New target
     recipe: packages/packages
     timeout: 60
     properties:
+      add_recipes_cq: "true"
       target_file: web_dart_unit_tests.yaml
       channel: master
       version_file: flutter_master.version
@@ -159,7 +157,6 @@ targets:
       package_sharding: "--shardIndex 1 --shardCount 2"
 
   - name: Linux_web web_dart_unit_test_shard_1 stable
-    bringup: true # New target
     recipe: packages/packages
     timeout: 60
     properties:
@@ -170,7 +167,6 @@ targets:
       package_sharding: "--shardIndex 0 --shardCount 2"
 
   - name: Linux_web web_dart_unit_test_shard_2 stable
-    bringup: true # New target
     recipe: packages/packages
     timeout: 60
     properties:

script/tool/lib/src/dart_test_command.dart

@@ -118,7 +118,9 @@ class DartTestCommand extends PackageLoopingCommand {
         'test',
         '--color',
         if (experiment.isNotEmpty) '--enable-experiment=$experiment',
-        if (platform != null) '--platform=$platform',
+        // Flutter defaults to VM mode (under a different name) and explicitly
+        // setting it is deprecated, so pass nothing in that case.
+        if (platform != null && platform != 'vm') '--platform=$platform',
       ],
       workingDir: package.directory,
     );

script/tool/test/dart_test_command_test.dart

@@ -231,6 +231,24 @@ void main() {
           ]));
     });
 
+    test('converts --platform=vm to no argument for flutter test', () async {
+      final RepositoryPackage plugin = createFakePlugin(
+        'some_plugin',
+        packagesDir,
+        extraFiles: <String>['test/empty_test.dart'],
+      );
+
+      await runCapturingPrint(runner, <String>['dart-test', '--platform=vm']);
+
+      expect(
+        processRunner.recordedCalls,
+        orderedEquals(<ProcessCall>[
+          ProcessCall(getFlutterCommand(mockPlatform),
+              const <String>['test', '--color'], plugin.path),
+        ]),
+      );
+    });
+
     test('runs in Chrome when requested for Flutter package', () async {
       final RepositoryPackage package = createFakePackage(
         'a_package',