Revert "Background finalization."

runtime/vm/heap.h

Index: runtime/vm/heap.h
diff --git a/runtime/vm/heap.h b/runtime/vm/heap.h
index d13150ecdd30cd8667cf8a8ffee7f191b6a2caef..6131bf319bfc2d3fd048900c7c5bf52a75db3f6f 100644
--- a/runtime/vm/heap.h
+++ b/runtime/vm/heap.h
@@ -256,10 +256,6 @@ class Heap {
   Monitor* barrier() const { return barrier_; }
   Monitor* barrier_done() const { return barrier_done_; }
 
-  Monitor* finalization_tasks_lock() const { return finalization_tasks_lock_; }
-  intptr_t finalization_tasks() const { return finalization_tasks_; }
-  void set_finalization_tasks(intptr_t count) { finalization_tasks_ = count; }
-
   bool ShouldPretenure(intptr_t class_id) const;
 
   void SetupExternalPage(void* pointer, uword size, bool is_executable) {
@@ -357,9 +353,6 @@ class Heap {
   Monitor* barrier_;
   Monitor* barrier_done_;
 
-  Monitor* finalization_tasks_lock_;
-  intptr_t finalization_tasks_;
-
   // GC stats collection.
   GCStats stats_;