Fix Mac warnings

src/property-details.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 41 matching lines @@
   // bitfield.  It is only used as a return value meaning the attributes of
   // a non-existent property.
 };
 
 
 namespace v8 {
 namespace internal {
 
 class Smi;
 template<class> class TypeImpl;
-class HeapTypeConfig;
+struct HeapTypeConfig;
 typedef TypeImpl<HeapTypeConfig> Type;
 class TypeInfo;
 
 // Type of properties.
 // Order of properties is significant.
 // Must fit in the BitField PropertyDetails::TypeField.
 // A copy of this is in mirror-debugger.js.
 enum PropertyType {
   // Only in slow mode.
   NORMAL                    = 0,
@@ skipping 247 matching lines @@
   PropertyDetails(int value, PropertyAttributes attributes) {
     value_ = AttributesField::update(value, attributes);
   }
 
   uint32_t value_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_DETAILS_H_