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

tests/utils/recursive_import_test.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.
 
 // Test of "recursive" imports using the dart2js compiler API.
 
 import "package:expect/expect.dart";
 import 'dart:async';
 import '../../sdk/lib/_internal/compiler/compiler.dart';
-import 'dart:uri';
 
 const CORE_LIB = """
 library core;
 class Object{
   operator==(other) {}
 }
 class bool {}
 class num {}
 class int {}
 class double{}
@@ skipping 75 matching lines @@
         warningCount++;
       } else if (kind == Diagnostic.ERROR) {
         errorCount++;
       } else {
         throw kind;
       }
     }
   }
 
   Future<String> result =
-      compile(new Uri.fromComponents(scheme: 'main'),
-              new Uri.fromComponents(scheme: 'lib', path: '/'),
-              new Uri.fromComponents(scheme: 'package', path: '/'),
+      compile(new Uri(scheme: 'main'),
+              new Uri(scheme: 'lib', path: '/'),
+              new Uri(scheme: 'package', path: '/'),
               provider, handler);
   result.then((String code) {
     Expect.isNull(code);
     Expect.isTrue(10 < count);
     // Two warnings for each time RECURSIVE_MAIN is read, except the
     // first time.
     Expect.equals(2 * (count - 1), warningCount);
     Expect.equals(1, errorCount);
   }, onError: (e) {
       throw 'Compilation failed';
   });
 }