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

tests/standalone/src/FileInvalidArgumentsTest.dart

 // Copyright (c) 2011, 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.
 
+#import("dart:io");
+
 class FileTest {
   static void testOpenInvalidArgs(name, [writable = false]) {
     var file = new File(name);
     try {
       file.openSync();
       Expect.fail('exception expected');
     } catch (var e) {
       Expect.isTrue(e is FileIOException);
       Expect.isTrue(e.toString().contains('open file'));
     }
@@ skipping 180 matching lines @@
   FileTest.testCreateInvalidArgs(0);
   FileTest.testReadListInvalidArgs(12, 0, 1);
   FileTest.testReadListInvalidArgs(new List(10), '0', 1);
   FileTest.testReadListInvalidArgs(new List(10), 0, '1');
   FileTest.testWriteByteInvalidArgs('asdf');
   FileTest.testWriteListInvalidArgs(12, 0, 1);
   FileTest.testWriteListInvalidArgs(new List(10), '0', 1);
   FileTest.testWriteListInvalidArgs(new List(10), 0, '1');
   FileTest.testFullPathInvalidArgs(12);
 }