Make IOSink implement StringSink

sdk/lib/_internal/compiler/implementation/dart2js.dart

Index: sdk/lib/_internal/compiler/implementation/dart2js.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart2js.dart b/sdk/lib/_internal/compiler/implementation/dart2js.dart
index 7be2db8c25176928cfbf6536e065d8e84ef61ab2..8b97d30b74666def962e7c55171d94ecae31ec58 100644
--- a/sdk/lib/_internal/compiler/implementation/dart2js.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart2js.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2013, 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.
 
@@ -293,7 +293,7 @@ void compile(List<String> argv) {
       if (sourceMapFileName != null) {
         String sourceMapTag = '//@ sourceMappingURL=$sourceMapFileName\n';
         sink.count += sourceMapTag.length;
-        output.addString(sourceMapTag);
+        output.write(sourceMapTag);
       }
       output.close();
       if (isPrimaryOutput) {
@@ -302,7 +302,7 @@ void compile(List<String> argv) {
     }
 
     var controller = new StreamController<String>();
-    controller.stream.listen(output.addString, onDone: onDone);
+    controller.stream.listen(output.write, onDone: onDone);
     sink = new CountingSink(controller);
     return sink;
   }