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

tools/testing/dart/test_progress.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("test_progress");
 
+#import("dart:io");
 #import("test_runner.dart");
 #import("test_suite.dart");
 
 class ProgressIndicator {
   ProgressIndicator(this._startTime, this._printTiming)
       : _tests = [], _failureSummary = [];
 
   factory ProgressIndicator.fromName(String name,
                                      Date startTime,
                                      bool printTiming) {
@@ skipping 309 matching lines @@
     var status = 'pass';
     if (test.output.unexpectedOutput) {
       status = 'fail';
     }
     var percent = ((_completedTests() / _foundTests) * 100).toInt().toString();
     print('Done ${test.configurationString} ${test.displayName}: $status');
     print('@@@STEP_CLEAR@@@');
     print('@@@STEP_TEXT@ $percent% +$_passedTests -$_failedTests @@@');
   }
 }