Split dart:builtin into dart:builtin and dart:io.

frog/minfrogc.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2012, 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('minfrogc');
 
+#import('dart:io');
 #import('file_system_vm.dart');
 #import('lang.dart');
 
 main() {
   List<String> argv = (new Options()).arguments;
 
   // Infer --out if there is none defined.
   var outFileDefined = false;
   for (var arg in argv) {
     if (arg.startsWith('--out=')) outFileDefined = true;
   }
 
   if (!outFileDefined) {
     argv.insertRange(0, 1, "--out=" + argv[argv.length-1] + ".js");
   }
 
   // TODO(dgrove) we're simulating node by placing the arguments to frogc
   // starting at index 2.
   argv.insertRange(0, 2, null);
 
   // TODO(dgrove) Until we have a way of getting the executable's path, we'll
   // run from '.'
   var homedir = (new File('.')).fullPathSync();
 
   if (!compile(homedir, argv, new VMFileSystem())) {
     print("Compilation failed");
     exit(1);
   }
 }