Revert "Update the test runner to use the new dart:io API" again

tools/testing/dart/multitest.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 multitest;
 
 import "dart:async";
 import "dart:io";
 import "test_suite.dart";
 import "utils.dart";
@@ skipping 119 matching lines @@
 class _Annotation {
   String key;
   String rest;
   List<String> outcomesList;
   _Annotation() {}
   factory _Annotation.from(String line) {
     if (!line.contains('///')) {
       return null;
     }
     var annotation = new _Annotation();
-    var parts = line.split('///')[1].split(':').map((s) => s.trim()).toList();
+    var parts = line.split('///')[1].split(':')
+        .mappedBy((s) => s.trim()).toList();
     annotation.key = parts[0];
     annotation.rest = parts[1];
     annotation.outcomesList = annotation.rest.split(',')
-        .map((s) => s.trim()).toList();
+        .mappedBy((s) => s.trim()).toList();
     return annotation;
   }
 }
 
 // Find all relative imports and copy them into the dir that contains
 // the generated tests.
 Set<Path> _findAllRelativeImports(Path topLibrary) {
   Set<Path> toSearch = new Set<Path>.from([topLibrary]);
-  Set<Path> foundImports = new Set<Path>();
+  Set<Path> foundImports = new HashSet<Path>();
   Path libraryDir = topLibrary.directoryPath;
   // Matches #import( or #source( followed by " or ' followed by anything
   // except dart:, dart-ext: or /, at the beginning of a line.
   RegExp relativeImportRegExp = new RegExp(
       '^#(import|source)[(]["\'](?!(dart:|dart-ext:|/))([^"\']*)["\']');
   while (!toSearch.isEmpty) {
     var thisPass = toSearch;
-    toSearch = new Set<Path>();
+    toSearch = new HashSet<Path>();
     for (Path filename in thisPass) {
       File f = new File.fromPath(filename);
       for (String line in f.readAsLinesSync()) {
         Match match = relativeImportRegExp.firstMatch(line);
         if (match != null) {
           Path relativePath = new Path(match.group(3));
           if (foundImports.contains(relativePath)) {
             continue;
           }
           if (relativePath.toString().contains('..')) {
@@ skipping 39 matching lines @@
   // Wait until all imports are copied before scheduling test cases.
   return Future.wait(futureCopies).then((_) {
     String baseFilename = filePath.filenameWithoutExtension;
     for (String key in tests.keys) {
       final Path multitestFilename =
           targetDir.append('${baseFilename}_$key.dart');
       final File file = new File.fromPath(multitestFilename);
 
       file.createSync();
       RandomAccessFile openedFile = file.openSync(FileMode.WRITE);
-      openedFile.writeStringSync(tests[key]);
+      var bytes = tests[key].charCodes;
+      openedFile.writeListSync(bytes, 0, bytes.length);
       openedFile.closeSync();
       Set<String> outcome = outcomes[key];
       bool enableFatalTypeErrors = outcome.contains('static type warning');
       bool hasRuntimeErrors = outcome.contains('runtime error');
       bool hasCompileError = outcome.contains('compile-time error');
       bool isNegativeIfChecked = outcome.contains('dynamic type error');
       doTest(multitestFilename,
              hasCompileError,
              hasRuntimeErrors,
              isNegativeIfChecked: isNegativeIfChecked,
@@ skipping 21 matching lines @@
     // TestSuite.forDirectory.
     split.removeLast();
   }
   String path = '${generatedTestDir.path}/${split.last}';
   Directory dir = new Directory(path);
   if (!dir.existsSync()) {
     dir.createSync();
   }
   return new Path(new File(path).fullPathSync());
 }