tweak fasta parser event debug code

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

 // Copyright (c) 2016, 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 fasta.body_builder;
 
 import 'package:kernel/ast.dart'
     hide InvalidExpression, InvalidInitializer, InvalidStatement;
 
 import 'package:kernel/class_hierarchy.dart' show ClassHierarchy;
@@ skipping 3345 matching lines @@
     }
   }
 
   @override
   void addCompileTimeError(Message message, int charOffset) {
     library.addCompileTimeError(message, charOffset, uri);
   }
 
   @override
   void debugEvent(String name) {
-    // printEvent(name);
+    // printEvent('BodyBuilder: $name');
   }
 
   @override
   StaticGet makeStaticGet(Member readTarget, Token token) {
     return new KernelStaticGet(readTarget)..fileOffset = offsetForToken(token);
   }
 }
 
 class Identifier {
   final Token token;
@@ skipping 450 matching lines @@
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return unhandled(asyncToken.lexeme, "asyncMarkerFromTokens",
         asyncToken.charOffset, null);
   }
 }