All strong mode cleaning of dart2js.

pkg/compiler/tool/dart2js_profile_many.dart

 // Copyright (c) 2014, 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.
 
 library dart2js.profile_many;
 
 import 'dart:async';
 
 import 'package:compiler/src/dart2js.dart' as cmdline;
 
 const String USAGE = """
 Usage: dart2js_profile_many.dart [OPTIONS] [FILES]
 
 Invokes dart2js separately for each file using the given options.
 This is for profiling multiple compilations in the Dart Observatory.
 """;
 
 printUsage() {
   print(USAGE);
 }
 
 void main(List<String> args) {
-  List options = [];
-  List files = [];
+  var options = <String>[];
+  var files = <String>[];
 
   for (String arg in args) {
     if (arg.startsWith('-')) {
       options.add(arg);
     } else {
       files.add(arg);
     }
   }
 
   if (files.length == 0) {
     printUsage();
     return;
   }
 
   cmdline.exitFunc = (code) {
     throw "Exit with code $code";
   };
 
   Future.forEach(files, (String file) {
     List subargs = [];
     subargs.addAll(options);
     subargs.add(file);
     return cmdline.compilerMain(subargs).catchError((e) {});
   }).then((_) {
     print("Done");
   });
 }