Before write-protecting a PageSpace, return bump allocation block to freelist.

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 VM_PAGES_H_
 #define VM_PAGES_H_
 
 #include "vm/freelist.h"
 #include "vm/globals.h"
 #include "vm/lockers.h"
@@ skipping 350 matching lines @@
                             bool is_locked);
   uword TryAllocateInFreshPage(intptr_t size,
                                HeapPage::PageType type,
                                GrowthPolicy growth_policy,
                                bool is_locked);
   uword TryAllocateDataBumpInternal(intptr_t size,
                                     GrowthPolicy growth_policy,
                                     bool is_locked);
   // Makes bump block walkable; do not call concurrently with mutator.
   void MakeIterable() const;
+  // Return any bump allocation block to the freelist.
+  void AbandonBumpAllocation();
   HeapPage* AllocatePage(HeapPage::PageType type);
   void FreePage(HeapPage* page, HeapPage* previous_page);
   HeapPage* AllocateLargePage(intptr_t size, HeapPage::PageType type);
   void TruncateLargePage(HeapPage* page, intptr_t new_object_size_in_bytes);
   void FreeLargePage(HeapPage* page, HeapPage* previous_page);
   void FreePages(HeapPage* pages);
   HeapPage* NextPageAnySize(HeapPage* page) const {
     ASSERT((pages_tail_ == NULL) || (pages_tail_->next() == NULL));
     ASSERT((exec_pages_tail_ == NULL) || (exec_pages_tail_->next() == NULL));
     if (page == pages_tail_) {
@@ skipping 51 matching lines @@
   friend class ExclusiveLargePageIterator;
   friend class PageSpaceController;
   friend class SweeperTask;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(PageSpace);
 };
 
 }  // namespace dart
 
 #endif  // VM_PAGES_H_