Generate message lookup in gen_l10n (flutter#50733)

Author: HansMuller

dev/tools/localization/bin/gen_l10n.dart

@@ -63,9 +63,8 @@ Future<void> main(List<String> arguments) async {
     exit(0);
   }
 
-  final String flutterRoot = Platform.environment['FLUTTER_ROOT'];
-  final String flutterBin = Platform.isWindows ? 'flutter.bat' : 'flutter';
-  final String flutterPath = flutterRoot == null ? flutterBin : path.join(flutterRoot, 'bin', flutterBin);
+  await precacheLanguageAndRegionTags();
+
   final String arbPathString = results['arb-dir'] as String;
   final String outputFileString = results['output-localization-file'] as String;
   final String templateArbFileName = results['template-arb-file'] as String;
@@ -74,6 +73,7 @@ Future<void> main(List<String> arguments) async {
 
   const local.LocalFileSystem fs = local.LocalFileSystem();
   final LocalizationsGenerator localizationsGenerator = LocalizationsGenerator(fs);
+
   try {
     localizationsGenerator
       ..initialize(
@@ -83,34 +83,13 @@ Future<void> main(List<String> arguments) async {
         classNameString: classNameString,
         preferredSupportedLocaleString: preferredSupportedLocaleString,
       )
-      ..parseArbFiles()
-      ..generateClassMethods()
-      ..generateOutputFile();
+      ..loadResources()
+      ..writeOutputFile();
   } on FileSystemException catch (e) {
     exitWithError(e.message);
   } on FormatException catch (e) {
     exitWithError(e.message);
   } on L10nException catch (e) {
     exitWithError(e.message);
   }
-
-  final ProcessResult pubGetResult = await Process.run(flutterPath, <String>['pub', 'get']);
-  if (pubGetResult.exitCode != 0) {
-    stderr.write(pubGetResult.stderr);
-    exit(1);
-  }
-
-  final ProcessResult generateFromArbResult = await Process.run(flutterPath, <String>[
-    'pub',
-    'run',
-    'intl_translation:generate_from_arb',
-    '--output-dir=${localizationsGenerator.l10nDirectory.path}',
-    '--no-use-deferred-loading',
-    localizationsGenerator.outputFile.path,
-    ...localizationsGenerator.arbPathStrings,
-  ]);
-  if (generateFromArbResult.exitCode != 0) {
-    stderr.write(generateFromArbResult.stderr);
-    exit(1);
-  }
 }