[heap] Fix address space leak in Unmapper

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 066bbfa7cdbff723921007e7dd0f2f47fb216613..fb01154957cbe6a4b09151daa4589d9b67135627 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -1097,7 +1097,7 @@ class SkipList {
 // A space acquires chunks of memory from the operating system. The memory
 // allocator allocates and deallocates pages for the paged heap spaces and large
 // pages for large object space.
-class MemoryAllocator {
+class V8_EXPORT_PRIVATE MemoryAllocator {
  public:
   // Unmapper takes care of concurrently unmapping and uncommitting memory
   // chunks.
@@ -1192,6 +1192,7 @@ class MemoryAllocator {
 
   enum FreeMode {
     kFull,
+    kAlreadyPooled,
     kPreFreeAndQueue,
     kPooledAndQueue,
   };
@@ -1648,7 +1649,7 @@ class AllocationStats BASE_EMBEDDED {
 //   words in size.
 // At least 16384 words (huge): This list is for objects of 2048 words or
 //   larger. Empty pages are also added to this list.
-class FreeList {
+class V8_EXPORT_PRIVATE FreeList {
  public:
   // This method returns how much memory can be allocated after freeing
   // maximum_freed memory.
@@ -1885,7 +1886,7 @@ class LocalAllocationBuffer {
   AllocationInfo allocation_info_;
 };
 
-class PagedSpace : public Space {
+class V8_EXPORT_PRIVATE PagedSpace : public Space {
  public:
   typedef PageIterator iterator;