Fixing build error on Win64.

src/spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1922 matching lines @@
 
 intptr_t FreeList::EvictFreeListItems(Page* p) {
   intptr_t sum = EvictFreeListItemsInList(&huge_list_, p);
 
   if (sum < Page::kObjectAreaSize) {
     sum += EvictFreeListItemsInList(&small_list_, p) +
         EvictFreeListItemsInList(&medium_list_, p) +
         EvictFreeListItemsInList(&large_list_, p);
   }
 
-  available_ -= sum;
+  available_ -= static_cast<int>(sum);
 
   return sum;
 }
 
 
 #ifdef DEBUG
 intptr_t FreeList::SumFreeList(FreeListNode* cur) {
   intptr_t sum = 0;
   while (cur != NULL) {
     ASSERT(cur->map() == HEAP->raw_unchecked_free_space_map());
@@ skipping 678 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal