Remove GC prologue and epilogue callbacks.

runtime/vm/pages.h

 // Copyright (c) 2011, 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.
 
 #ifndef RUNTIME_VM_PAGES_H_
 #define RUNTIME_VM_PAGES_H_
 
 #include "vm/freelist.h"
 #include "vm/globals.h"
 #include "vm/lockers.h"
@@ skipping 232 matching lines @@
   void VisitObjectPointers(ObjectPointerVisitor* visitor) const;
 
   RawObject* FindObject(FindObjectVisitor* visitor,
                         HeapPage::PageType type) const;
 
   // Checks if enough time has elapsed since the last attempt to collect
   // code.
   bool ShouldCollectCode();
 
   // Collect the garbage in the page space using mark-sweep.
-  void MarkSweep(bool invoke_api_callbacks);
+  void MarkSweep();
 
   void AddRegionsToObjectSet(ObjectSet* set) const;
 
   void InitGrowthControl() {
     page_space_controller_.set_last_usage(usage_);
     page_space_controller_.Enable();
   }
 
   void SetGrowthControlState(bool state) {
     if (state) {
@@ skipping 171 matching lines @@
   friend class HeapIterationScope;
   friend class PageSpaceController;
   friend class SweeperTask;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(PageSpace);
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_PAGES_H_