Remove background finalization.

runtime/vm/thread.cc

 // Copyright (c) 2015, 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.
 
 #include "vm/thread.h"
 
 #include "vm/compiler_stats.h"
 #include "vm/dart_api_state.h"
 #include "vm/growable_array.h"
 #include "vm/isolate.h"
@@ skipping 276 matching lines @@
     case kUnknownTask:
       return "kUnknownTask";
     case kMutatorTask:
       return "kMutatorTask";
     case kCompilerTask:
       return "kCompilerTask";
     case kSweeperTask:
       return "kSweeperTask";
     case kMarkerTask:
       return "kMarkerTask";
-    case kFinalizerTask:
-      return "kFinalizerTask";
     default:
       UNREACHABLE();
       return "";
   }
 }
 
 
 RawStackTrace* Thread::async_stack_trace() const {
   return async_stack_trace_;
 }
@@ skipping 598 matching lines @@
 
 DisableThreadInterruptsScope::~DisableThreadInterruptsScope() {
   if (thread() != NULL) {
     OSThread* os_thread = thread()->os_thread();
     ASSERT(os_thread != NULL);
     os_thread->EnableThreadInterrupts();
   }
 }
 
 }  // namespace dart