Move mojo and mojom from mojo/public/dart to mojo/dart/packages

mojo/dart/packages/mojom/lib/src/utils.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 library mojom.utils;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 116 matching lines @@
   return 0;
 }
 
 /// Is any element of [haystack] a prefix of [needle]?
 bool containsPrefix(String needle, List<String> haystack) {
   if (haystack == null) return false;
   var match =
       haystack.firstWhere((p) => needle.startsWith(p), orElse: () => null);
   return match != null;
 }