Add Stdio.readByteSync and Stdio.readLineSync.

tests/standalone/io/stdin_sync_test.dart

+// Copyright (c) 2013, 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";
+
+void main() {
+  var script = new Path(Platform.script).directoryPath;
+  script = script.append("stdin_sync_script.dart");
+  print(script.toNativePath());
+  Process.start(Platform.executable, [script.toNativePath()]).then((process) {
+    process.stdin.write("hej\x01\x00\x0d\x0a\x0a4\x0a");
+    process.stdin.close();
+    process.stdout
+        .transform(new StringDecoder())
+        .transform(new LineTransformer())
+        .fold(new StringBuffer(), (b, d) => b..write(d))
+        .then((data) {
+          if (data.toString() != 'true') throw "Bad output: '$data'";
+        });
+  });
+}