Make deferred loading of message libraries optional

pkg/intl/bin/generate_from_arb.dart

 #!/usr/bin/env dart
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * A main program that takes as input a source Dart file and a number
  * of ARB files representing translations of messages from the corresponding
  * Dart file. See extract_to_arb.dart and make_hardcoded_translation.dart.
  *
@@ skipping 22 matching lines @@
 
 main(List<String> args) {
   var targetDir;
   var parser = new ArgParser();
   parser.addFlag("suppress-warnings", defaultsTo: false,
       callback: (x) => suppressWarnings = x);
   parser.addOption("output-dir", defaultsTo: '.',
       callback: (x) => targetDir = x);
   parser.addOption("generated-file-prefix", defaultsTo: '',
       callback: (x) => generatedFilePrefix = x);
+  parser.addFlag("use-deferred-loading", defaultsTo: true,
+      callback: (x) => useDeferredLoading = x);
   parser.parse(args);
   var dartFiles = args.where((x) => x.endsWith("dart")).toList();
   var jsonFiles = args.where((x) => x.endsWith(".arb")).toList();
   if (dartFiles.length == 0 || jsonFiles.length == 0) {
     print('Usage: generate_from_arb [--output-dir=<dir>]'
+        ' [--[no-]use-deferred-loading]'
         ' [--generated-file-prefix=<prefix>] file1.dart file2.dart ...'
         ' translation1_<languageTag>.arb translation2.arb ...');
     exit(0);
   }
 
   // We're re-parsing the original files to find the corresponding messages,
   // so if there are warnings extracting the messages, suppress them.
   suppressWarnings = true;
   var allMessages = dartFiles.map((each) => parseFile(new File(each)));
 
@@ skipping 74 matching lines @@
 
   // We know that our [id] is the name of the message, which is used as the
   //key in [messages].
   List<MainMessage> _findOriginals() => originalMessages = messages[id];
 }
 
 final pluralAndGenderParser = 
     removeDuplicates(removeSetables(new ICUParser().message));
 final plainParser = 
     removeDuplicates(removeSetables(new ICUParser().nonIcuMessage));