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

src/objects-inl.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 4937 matching lines @@
   running_hash ^= (running_hash >> 6);
   return running_hash;
 }
 
 
 uint32_t StringHasher::GetHashCore(uint32_t running_hash) {
   running_hash += (running_hash << 3);
   running_hash ^= (running_hash >> 11);
   running_hash += (running_hash << 15);
   if ((running_hash & String::kHashBitMask) == 0) {
-    return 27;
+    return kZeroHash;
   }
   return running_hash;
 }
 
 
 void StringHasher::AddCharacter(uint32_t c) {
   if (c > unibrow::Utf16::kMaxNonSurrogateCharCode) {
     AddSurrogatePair(c);  // Not inlined.
     return;
   }
@@ skipping 571 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_