Fix OOM bug 3976.

src/heap/spaces.h

 // Copyright 2011 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_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
@@ skipping 1853 matching lines @@
 
   // Returns the number of total pages in this space.
   int CountTotalPages();
 
   // Return size of allocatable area on a page in this space.
   inline int AreaSize() { return area_size_; }
 
   void CreateEmergencyMemory();
   void FreeEmergencyMemory();
   void UseEmergencyMemory();
+  intptr_t MaxEmergencyMemoryAllocated();
 
   bool HasEmergencyMemory() { return emergency_memory_ != NULL; }
 
  protected:
   FreeList* free_list() { return &free_list_; }
 
   int area_size_;
 
   // Maximum capacity of this space.
   intptr_t max_capacity_;
@@ skipping 979 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_SPACES_H_