Merge the dart:uri library into dart:core and update the Uri class

pkg/stack_trace/lib/src/frame.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 frame;
 
-import 'dart:uri';
 
 import 'package:pathos/path.dart' as path;
 
 import 'trace.dart';
 import 'utils.dart';
 
 final _nativeFrameRegExp = new RegExp(
     r'^#\d+\s+([^\s].*) \((.+):(\d+):(\d+)\)$');
 
 /// A single stack frame. Each frame points to a precise location in Dart code.
@@ skipping 69 matching lines @@
 
     var uri = Uri.parse(match[2]);
     var member = match[1].replaceAll("<anonymous closure>", "<fn>");
     return new Frame(uri, int.parse(match[3]), int.parse(match[4]), member);
   }
 
   Frame(this.uri, this.line, this.column, this.member);
 
   String toString() => '$location in $member';
 }