Refactor CompilerOutput

pkg/compiler/lib/src/ssa/ssa_tracer.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.
 
 library ssa.tracer;
 
-import 'dart:async' show EventSink;
-
+import '../../compiler_new.dart' show OutputSink;
 import '../diagnostics/invariant.dart' show DEBUG_MODE;
 import '../js_backend/namer.dart' show Namer;
 import '../tracer.dart';
 import '../world.dart' show ClosedWorld;
 import 'nodes.dart';
 
 /**
  * Outputs SSA code in a format readable by Hydra IR.
  * Tracing is disabled by default, see ../tracer.dart for how
  * to enable it.
  */
 class HTracer extends HGraphVisitor with TracerUtil {
   final ClosedWorld closedWorld;
   final Namer namer;
-  final EventSink<String> output;
+  final OutputSink output;
 
   HTracer(this.output, this.closedWorld, this.namer);
 
   void traceGraph(String name, HGraph graph) {
     DEBUG_MODE = true;
     tag("cfg", () {
       printProperty("name", name);
       visitDominatorTree(graph);
     });
   }
@@ skipping 526 matching lines @@
   }
 
   String visitAwait(HAwait node) {
     return "Await: ${temporaryId(node.inputs[0])}";
   }
 
   String visitYield(HYield node) {
     return "Yield${node.hasStar ? "*" : ""}: ${temporaryId(node.inputs[0])}";
   }
 }