Fix two-char hash to use correct fallback for zero hashes.

src/objects.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 7362 matching lines @@
 
   static const int kContainsCachedArrayIndexMask =
       (~kMaxCachedArrayIndexLength << kArrayIndexHashLengthShift) |
       kIsNotArrayIndexMask;
 
   // Value of empty hash field indicating that the hash is not computed.
   static const int kEmptyHashField =
       kIsNotArrayIndexMask | kHashNotComputedMask;
 
   // Value of hash field containing computed hash equal to zero.
-  static const int kZeroHash = kIsNotArrayIndexMask;
+  static const int kEmptyStringHash = kIsNotArrayIndexMask;
 
   // Maximal string length.
   static const int kMaxLength = (1 << (32 - 2)) - 1;
 
   // Max length for computing hash. For strings longer than this limit the
   // string length is used as the hash value.
   static const int kMaxHashCalcLength = 16383;
 
   // Limit for truncation in short printing.
   static const int kMaxShortPrintLength = 1024;
@@ skipping 1561 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_