Use new library/import syntax in dart2js.

sdk/lib/_internal/compiler/implementation/util/uri_extras.dart

Index: sdk/lib/_internal/compiler/implementation/util/uri_extras.dart
diff --git a/sdk/lib/_internal/compiler/implementation/util/uri_extras.dart b/sdk/lib/_internal/compiler/implementation/util/uri_extras.dart
index aa2f93a5d3abef45662b9769cb7de8bd096c8071..fed5f154cbcda33b267e31929e8254231f205e87 100644
--- a/sdk/lib/_internal/compiler/implementation/util/uri_extras.dart
+++ b/sdk/lib/_internal/compiler/implementation/util/uri_extras.dart
@@ -2,10 +2,10 @@
 // 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('uri_extras');
+library uri_extras;
 
-#import('dart:math');
-#import('dart:uri');
+import 'dart:math';
+import 'dart:uri';
 
 String relativize(Uri base, Uri uri, bool isWindows) {
   if (!base.path.startsWith('/')) {