More cleanup regarding the maximum non-large object allocation size.

src/spaces.h

 // 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 766 matching lines @@
 
   // Page size in bytes.  This must be a multiple of the OS page size.
   static const int kPageSize = 1 << kPageSizeBits;
 
   // Object area size in bytes.
   static const int kNonCodeObjectAreaSize = kPageSize - kObjectStartOffset;
 
   // Maximum object size that fits in a page. Objects larger than that size
   // are allocated in large object space and are never moved in memory. This
   // also applies to new space allocation, since objects are never migrated
-  // from new space to large object space.
-  static const int kMaxNonCodeHeapObjectSize = kNonCodeObjectAreaSize;
+  // from new space to large object space.  Takes double alignment into account.
+  static const int kMaxNonCodeHeapObjectSize =
+      kNonCodeObjectAreaSize - kPointerSize;
 
   // Page size mask.
   static const intptr_t kPageAlignmentMask = (1 << kPageSizeBits) - 1;
 
   inline void ClearGCFields();
 
   static inline Page* Initialize(Heap* heap,
                                  MemoryChunk* chunk,
                                  Executability executable,
                                  PagedSpace* owner);
@@ skipping 2078 matching lines @@
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_H_