Add library mapping.

dart/lib/compiler/implementation/dart2js.dart

 // 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('dart2js');
 
 #import('dart:io');
 #import('dart:utf');
 
 #import('../../uri/uri.dart');
 #import('../compiler.dart', prefix: 'api');
-#import('io/io.dart', prefix: 'io');
 #import('colors.dart');
 #import('source_file.dart');
 
 String relativize(Uri base, Uri uri) {
   if (base.scheme == 'file' &&
       base.scheme == uri.scheme &&
       base.userInfo == uri.userInfo &&
       base.domain == uri.domain &&
       base.port == uri.port &&
       uri.query == "" && uri.fragment == "") {
@@ skipping 14 matching lines @@
     for (int i = common; i < uriParts.length - 1; i++) {
       sb.add('${uriParts[i]}/');
     }
     sb.add('${uriParts.last()}');
     return sb.toString();
   }
   return uri.toString();
 }
 
 void compile(List<String> argv) {
-  Uri cwd = new Uri(scheme: 'file', path: io.getCurrentDirectory());
+  Uri cwd = new Uri(scheme: 'file', path: getCurrentDirectory());
   bool throwOnError = false;
   bool showWarnings = true;
   bool verbose = false;
   Uri libraryRoot = cwd;
   Uri out = cwd.resolve('out.js');
 
   List<String> arguments = <String>[];
   for (String argument in argv) {
     if ('--throw-on-error' == argument) {
       throwOnError = true;
@@ skipping 86 matching lines @@
 }
 
 String readAll(String filename) {
   var file = (new File(filename)).openSync();
   var length = file.lengthSync();
   var buffer = new List<int>(length);
   var bytes = file.readListSync(buffer, 0, length);
   file.closeSync();
   return new String.fromCharCodes(new Utf8Decoder(buffer).decodeRest());
 }
+
+String getCurrentDirectory() {
+  String dir = new File(".").fullPathSync();
+  if (dir.endsWith("/")) return dir;
+  return "$dir/";
+}