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

tests/compiler/dart2js/metadata_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.
 
 import "package:expect/expect.dart";
 import 'compiler_helper.dart';
 import 'parser_helper.dart';
 
 void checkPosition(Spannable spannable, Node node, String source, compiler) {
   SourceSpan span = compiler.spanFromSpannable(spannable);
@@ skipping 125 matching lines @@
 }
 
 void testTopLevelFieldMetadata() {
   checkAnnotation('foo', 'var foo;');
 }
 
 void testLibraryTags() {
   void compileAndCheckLibrary(
       String source,
       Link<MetadataAnnotation> extractMetadata(LibraryElement element)) {
-    Uri partUri = new Uri.fromComponents(scheme: 'source', path: 'part.dart');
+    Uri partUri = new Uri(scheme: 'source', path: 'part.dart');
     String partSource = '@native part of foo;';
 
-    Uri libUri = new Uri.fromComponents(scheme: 'source', path: 'lib.dart');
+    Uri libUri = new Uri(scheme: 'source', path: 'lib.dart');
     String libSource = 'library lib;';
 
-    Uri uri = new Uri.fromComponents(scheme: 'source', path: 'main.dart');
+    Uri uri = new Uri(scheme: 'source', path: 'main.dart');
 
-    Uri async = new Uri.fromComponents(scheme: 'dart', path: 'async');
+    Uri async = new Uri(scheme: 'dart', path: 'async');
 
     var compiler = compilerFor(source, uri)
         ..registerSource(partUri, partSource)
         ..registerSource(libUri, libSource)
         ..registerSource(async, 'class DeferredLibrary {}')
         ..runCompiler(uri);
     compiler.enqueuer.resolution.queueIsClosed = false;
     LibraryElement element = compiler.libraries['$uri'];
     Expect.isNotNull(element, 'Cannot find $uri');
 
@@ skipping 41 matching lines @@
   compileAndCheckLibrary(source,
                          (e) => e.compilationUnits.first.partTag.metadata);
 }
 
 void main() {
   testClassMetadata();
   testTopLevelMethodMetadata();
   testTopLevelFieldMetadata();
   testLibraryTags();
 }