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

tests/compiler/dart2js/type_test_helper.dart

Index: tests/compiler/dart2js/type_test_helper.dart
diff --git a/tests/compiler/dart2js/type_test_helper.dart b/tests/compiler/dart2js/type_test_helper.dart
index 7f1eaa22a0b07f232b3b161e72a5bc4b996e17cb..db1a43f8a95153a5fbaaba5a173903dd09a89160 100644
--- a/tests/compiler/dart2js/type_test_helper.dart
+++ b/tests/compiler/dart2js/type_test_helper.dart
@@ -23,7 +23,7 @@ class TypeEnvironment {
   final MockCompiler compiler;
 
   factory TypeEnvironment(String source) {
-    var uri = new Uri.fromComponents(scheme: 'source');
+    var uri = new Uri(scheme: 'source');
     MockCompiler compiler = compilerFor('''
         main() {}
         $source''',