no need .toList() before .join() (#30304)

dev/tools/localization/gen_localizations.dart

@@ -272,7 +272,7 @@ String generateTranslationBundles() {
 ///
 ///  * [getMaterialTranslation], whose documentation describes these values.
 final Set<String> kSupportedLanguages = HashSet<String>.from(const <String>[
-${languageCodes.map<String>((String value) => "  '$value', // ${describeLocale(value)}").toList().join('\n')}
+${languageCodes.map<String>((String value) => "  '$value', // ${describeLocale(value)}").join('\n')}
 ]);
 
 /// Creates a [GlobalMaterialLocalizations] instance for the given `locale`.

examples/catalog/bin/sample_page.dart

@@ -217,10 +217,10 @@ void generate(String commit) {
     <String, String>{
       'imports': samples.map<String>((SampleInfo page) {
         return "import '${page.importPath}' show ${page.sampleClass};\n";
-      }).toList().join(),
+      }).join(),
       'widgets': samples.map<String>((SampleInfo sample) {
         return 'new ${sample.sampleClass}(),\n';
-      }).toList().join(),
+      }).join(),
     },
   );
 
@@ -232,7 +232,7 @@ void generate(String commit) {
     <String, String>{
       'paths': samples.map<String>((SampleInfo sample) {
         return "'${outputFile(sample.sourceName + '.png').path}'";
-      }).toList().join(',\n'),
+      }).join(',\n'),
     },
   );