Emit to StreamCodeOutput instead of CodeBuffer.

pkg/compiler/lib/src/js_emitter/old_emitter/metadata_emitter.dart

 // 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.
 
 part of dart2js.js_emitter;
 
 class MetadataEmitter extends CodeEmitterHelper {
   /// A list of JS expressions that represent metadata, parameter names and
   /// type, and return types.
   final List<String> globalMetadata = [];
@@ skipping 85 matching lines @@
     return addGlobalMetadata('"$name"');
   }
 
   int addGlobalMetadata(String string) {
     return globalMetadataMap.putIfAbsent(string, () {
       globalMetadata.add(string);
       return globalMetadata.length - 1;
     });
   }
 
-  void emitMetadata(CodeBuffer buffer) {
+  void emitMetadata(CodeOutput output) {
     String metadataAccess = emitter.generateEmbeddedGlobalAccessString(
           embeddedNames.METADATA);
-    buffer.write('$metadataAccess$_=$_[');
+    output.add('$metadataAccess$_=$_[');
     for (String metadata in globalMetadata) {
       if (metadata is String) {
         if (metadata != 'null') {
-          buffer.write(metadata);
+          output.add(metadata);
         }
       } else {
         throw 'Unexpected value in metadata: ${Error.safeToString(metadata)}';
       }
-      buffer.write(',$n');
+      output.add(',$n');
     }
-    buffer.write('];$n');
+    output.add('];$n');
   }
 
   List<int> computeMetadata(FunctionElement element) {
     return compiler.withCurrentElement(element, () {
       if (!mustEmitMetadataFor(element)) return const <int>[];
       List<int> metadata = <int>[];
       Link link = element.metadata;
       // TODO(ahe): Why is metadata sometimes null?
       if (link != null) {
         for (; !link.isEmpty; link = link.tail) {
           metadata.add(reifyMetadata(link.head));
         }
       }
       return metadata;
     });
   }
 }