Explicitly pass the web renderer into the tests. (flutter#6140)

The web tests currently all assume to be using the html renderer. `flutter test` previously erroneously was serving files for the HTML renderer by default (which is not the intended behavior). After this was fixed, the tests started running on the CanvasKit renderer and some of them broke. If we are relying on the html renderer, we should explicitly pass it when running `flutter test`

Author: eyebrowsoffire

script/tool/lib/src/dart_test_command.dart

@@ -98,9 +98,11 @@ class DartTestCommand extends PackageLoopingCommand {
       platform = 'chrome';
     }
 
+    // All the web tests assume the html renderer currently.
+    final String? webRenderer = (platform == 'chrome') ? 'html' : null;
     bool passed;
     if (package.requiresFlutter()) {
-      passed = await _runFlutterTests(package, platform: platform);
+      passed = await _runFlutterTests(package, platform: platform, webRenderer: webRenderer);
     } else {
       passed = await _runDartTests(package, platform: platform);
     }
@@ -109,7 +111,7 @@ class DartTestCommand extends PackageLoopingCommand {
 
   /// Runs the Dart tests for a Flutter package, returning true on success.
   Future<bool> _runFlutterTests(RepositoryPackage package,
-      {String? platform}) async {
+      {String? platform, String? webRenderer}) async {
     final String experiment = getStringArg(kEnableExperiment);
 
     final int exitCode = await processRunner.runAndStream(
@@ -121,6 +123,7 @@ class DartTestCommand extends PackageLoopingCommand {
         // 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=$platform',
+        if (webRenderer != null) '--web-renderer=$webRenderer',
       ],
       workingDir: package.directory,
     );

script/tool/lib/src/drive_examples_command.dart

@@ -119,6 +119,7 @@ class DriveExamplesCommand extends PackageLoopingCommand {
           'web-server',
           '--web-port=7357',
           '--browser-name=chrome',
+          '--web-renderer=html',
           if (platform.environment.containsKey('CHROME_EXECUTABLE'))
             '--chrome-binary=${platform.environment['CHROME_EXECUTABLE']}',
         ],

script/tool/test/dart_test_command_test.dart

@@ -265,7 +265,7 @@ void main() {
         orderedEquals(<ProcessCall>[
           ProcessCall(
               getFlutterCommand(mockPlatform),
-              const <String>['test', '--color', '--platform=chrome'],
+              const <String>['test', '--color', '--platform=chrome', '--web-renderer=html'],
               package.path),
         ]),
       );
@@ -289,7 +289,7 @@ void main() {
         orderedEquals(<ProcessCall>[
           ProcessCall(
               getFlutterCommand(mockPlatform),
-              const <String>['test', '--color', '--platform=chrome'],
+              const <String>['test', '--color', '--platform=chrome', '--web-renderer=html'],
               plugin.path),
         ]),
       );
@@ -314,7 +314,7 @@ void main() {
         orderedEquals(<ProcessCall>[
           ProcessCall(
               getFlutterCommand(mockPlatform),
-              const <String>['test', '--color', '--platform=chrome'],
+              const <String>['test', '--color', '--platform=chrome', '--web-renderer=html'],
               plugin.path),
         ]),
       );
@@ -339,7 +339,7 @@ void main() {
         orderedEquals(<ProcessCall>[
           ProcessCall(
               getFlutterCommand(mockPlatform),
-              const <String>['test', '--color', '--platform=chrome'],
+              const <String>['test', '--color', '--platform=chrome', '--web-renderer=html'],
               plugin.path),
         ]),
       );
@@ -409,7 +409,7 @@ void main() {
         orderedEquals(<ProcessCall>[
           ProcessCall(
               getFlutterCommand(mockPlatform),
-              const <String>['test', '--color', '--platform=chrome'],
+              const <String>['test', '--color', '--platform=chrome', '--web-renderer=html'],
               plugin.path),
         ]),
       );

script/tool/test/drive_examples_command_test.dart

@@ -678,6 +678,7 @@ void main() {
                   'web-server',
                   '--web-port=7357',
                   '--browser-name=chrome',
+                  '--web-renderer=html',
                   '--driver',
                   'test_driver/integration_test.dart',
                   '--target',
@@ -726,6 +727,7 @@ void main() {
                   'web-server',
                   '--web-port=7357',
                   '--browser-name=chrome',
+                  '--web-renderer=html',
                   '--driver',
                   'test_driver/integration_test.dart',
                   '--target',
@@ -777,6 +779,7 @@ void main() {
                   'web-server',
                   '--web-port=7357',
                   '--browser-name=chrome',
+                  '--web-renderer=html',
                   '--chrome-binary=/path/to/chrome',
                   '--driver',
                   'test_driver/integration_test.dart',
@@ -1223,6 +1226,7 @@ void main() {
                   'web-server',
                   '--web-port=7357',
                   '--browser-name=chrome',
+                  '--web-renderer=html',
                   '--driver',
                   'test_driver/integration_test.dart',
                   '--target',
@@ -1237,6 +1241,7 @@ void main() {
                   'web-server',
                   '--web-port=7357',
                   '--browser-name=chrome',
+                  '--web-renderer=html',
                   '--driver',
                   'test_driver/integration_test.dart',
                   '--target',
@@ -1334,6 +1339,7 @@ void main() {
                     'web-server',
                     '--web-port=7357',
                     '--browser-name=chrome',
+                    '--web-renderer=html',
                     '--driver',
                     'test_driver/integration_test.dart',
                     '--target',
@@ -1413,6 +1419,7 @@ void main() {
                     'web-server',
                     '--web-port=7357',
                     '--browser-name=chrome',
+                    '--web-renderer=html',
                     '--driver',
                     'test_driver/integration_test.dart',
                     '--target',