Add a couple functions to package:stack_trace.

pkg/stack_trace/lib/src/utils.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.
+
+library stack_trace.src.utils;
+
+/// Returns [string] with enough spaces added to the end to make it [length]
+/// characters long.
+String padRight(String string, int length) {
+  if (string.length >= length) return string;
+
+  var result = new StringBuffer();
+  result.write(string);
+  for (var i = 0; i < length - string.length; i++) {
+    result.write(' ');
+  }
+
+  return result.toString();
+}
+