Avoid allocating a whole new page for two one-element arrays when finalizing the VM isolate.

runtime/vm/pages.h

Index: runtime/vm/pages.h
diff --git a/runtime/vm/pages.h b/runtime/vm/pages.h
index 7699625cc978d36801011d479bbccd7d3c89504a..729e94f6a47f36744d6c13629804573d5ce2112a 100644
--- a/runtime/vm/pages.h
+++ b/runtime/vm/pages.h
@@ -320,6 +320,9 @@ class PageSpace {
 
   void SetupImagePage(void* pointer, uword size, bool is_executable);
 
+  // Return any bump allocation block to the freelist.
+  void AbandonBumpAllocation();
+
  private:
   // Ids for time and data records in Heap::GCStats.
   enum {
@@ -353,8 +356,6 @@ class PageSpace {
                                     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);