Unify most of our utf8 implementations. This takes the implementation

frog/leg/scanner/source_list.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.
 
 final List<String> argv = const <String>[
 '../client/dom/common/implementation.dart',
 '../client/dom/common/public.dart',
 '../client/dom/dom.dart',
 '../client/dom/dom_dummy.dart',
 '../client/dom/generated/src/interface/AbstractWorker.dart',
@@ skipping 1494 matching lines @@
 '../corelib/src/pattern.dart',
 '../corelib/src/queue.dart',
 '../corelib/src/regexp.dart',
 '../corelib/src/set.dart',
 '../corelib/src/stopwatch.dart',
 '../corelib/src/string.dart',
 '../corelib/src/string_buffer.dart',
 '../corelib/src/strings.dart',
 '../corelib/src/time_zone.dart',
 '../lib/json/json.dart',
+'../lib/utf/utf.dart',
+'../lib/utf/utf_coer.dart',
+'../lib/utf/utf8.dart',
+'../lib/utf/utf16.dart',
+'../lib/utf/utf32.dart',
 '../lib/uri/uri.dart',
-'../lib/utf8/utf8.dart',
 '../samples/actors/core/actors-dom.dart',
 '../samples/actors/core/actors-interface.dart',
 '../samples/actors/core/actors-term.dart',
 '../samples/actors/core/actors-ui.dart',
 '../samples/actors/core/actors-web.dart',
 '../samples/actors/core/actors.dart',
 '../samples/actors/samples/dartcombat/dartcombat.dart',
 '../samples/actors/samples/dartcombat/dartcombatlib.dart',
 '../samples/actors/samples/dartcombat/grids.dart',
 '../samples/actors/samples/dartcombat/player.dart',
@@ skipping 270 matching lines @@
 './lib/num.dart',
 './lib/string_buffer.dart',
 './member_set.dart',
 './method_data.dart',
 './minfrog.dart',
 './minfrogc.dart',
 './reader.dart',
 './samples/ifrog.dart',
 './server/frog_server.dart',
 './server/toss.dart',
-'./server/utf8.dart',
 './source.dart',
 './token.dart',
 './tokenizer.dart',
 './tokenizer.g.dart',
 './tree.dart',
 './tree.g.dart',
 './utils.dart'];