Revert of [heap] Don't unmap new space pages while sweeping is active

src/heap/mark-compact.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_MARK_COMPACT_H_
 #define V8_HEAP_MARK_COMPACT_H_
 
 #include <deque>
 
 #include "src/base/bits.h"
@@ skipping 297 matching lines @@
     void AddPage(AllocationSpace space, Page* page);
     void AddLatePage(AllocationSpace space, Page* page);
 
     int ParallelSweepSpace(AllocationSpace identity, int required_freed_bytes,
                            int max_pages = 0);
     int ParallelSweepPage(Page* page, AllocationSpace identity);
 
     void StartSweeping();
     void StartSweepingHelper(AllocationSpace space_to_start);
     void EnsureCompleted();
+    void EnsureNewSpaceCompleted();
     bool IsSweepingCompleted();
     void SweepOrWaitUntilSweepingCompleted(Page* page);
 
     void AddSweptPageSafe(PagedSpace* space, Page* page);
     Page* GetSweptPageSafe(PagedSpace* space);
 
    private:
     static const int kAllocationSpaces = LAST_PAGED_SPACE + 1;
 
     template <typename Callback>
@@ skipping 440 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_H_