Remove background finalization.

runtime/observatory/lib/src/service/object.dart

 // Copyright (c) 2014, 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 service;
 
 // Some value smaller than the object ring, so requesting a large array
 // doesn't result in an expired ref because the elements lapped it in the
 // object ring.
 const int kDefaultFieldLimit = 100;
@@ skipping 3121 matching lines @@
         _kindString = 'compiler';
         break;
       case "kSweeperTask":
         _kind = M.ThreadKind.sweeperTask;
         _kindString = 'sweeper';
         break;
       case "kMarkerTask":
         _kind = M.ThreadKind.markerTask;
         _kindString = 'marker';
         break;
-      case "kFinalizerTask":
-        _kind = M.ThreadKind.finalizerTask;
-        _kindString = 'finalizer';
-        break;
       default:
         assert(false);
     }
 
     _zoneHighWatermark = int.parse(map['_zoneHighWatermark']);
     _zoneCapacity = int.parse(map['_zoneCapacity']);
   }
 }
 
 class Zone implements M.Zone {
@@ skipping 1472 matching lines @@
     var v = list[i];
     if ((v is Map) && _isServiceMap(v)) {
       list[i] = owner.getFromMap(v);
     } else if (v is List) {
       _upgradeList(v, owner);
     } else if (v is Map) {
       _upgradeMap(v, owner);
     }
   }
 }