Use linear backing store for hidden properties to save memory.

src/v8globals.h

 // Copyright 2012 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 107 matching lines @@
 class Assembler;
 class AssertNoAllocation;
 class Code;
 class CodeGenerator;
 class CodeStub;
 class Context;
 class Debug;
 class Debugger;
 class DebugInfo;
 class Descriptor;
+class HiddenPropertiesArray;
 class DescriptorArray;
 class TransitionArray;
 class ExternalReference;
 class FixedArray;
 class FunctionTemplateInfo;
 class MemoryChunk;
 class SeededNumberDictionary;
 class UnseededNumberDictionary;
 class StringDictionary;
 template <typename T> class Handle;
@@ skipping 410 matching lines @@
 
 enum ClearExceptionFlag {
   KEEP_EXCEPTION,
   CLEAR_EXCEPTION
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_V8GLOBALS_H_