Use new library/import syntax in dart2js.

sdk/lib/_internal/compiler/implementation/source_map_builder.dart

Index: sdk/lib/_internal/compiler/implementation/source_map_builder.dart
diff --git a/sdk/lib/_internal/compiler/implementation/source_map_builder.dart b/sdk/lib/_internal/compiler/implementation/source_map_builder.dart
index a29b0fe3f428380545ab329a073da3dfeb8f2001..0670ee20218d1d3d9b5ebb8acc7abbf91a7cf778 100644
--- a/sdk/lib/_internal/compiler/implementation/source_map_builder.dart
+++ b/sdk/lib/_internal/compiler/implementation/source_map_builder.dart
@@ -2,12 +2,12 @@
 // 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('source_map_builder');
+library source_map_builder;
 
-#import('dart:json');
+import 'dart:json';
 
-#import('scanner/scannerlib.dart');
-#import('source_file.dart');
+import 'scanner/scannerlib.dart';
+import 'source_file.dart';
 
 class SourceMapBuilder {
   static const int VLQ_BASE_SHIFT = 5;