Fix the logic that should ensure that a string cannot have

src/objects.cc

 // 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 11426 matching lines @@
     hash += hash << 10;
     hash ^= hash >> 6;
     // Char 2.
     hash += c2;
     hash += hash << 10;
     hash ^= hash >> 6;
     // GetHash.
     hash += hash << 3;
     hash ^= hash >> 11;
     hash += hash << 15;
-    if (hash == 0) hash = 27;
+    if ((hash & String::kHashBitMask) == 0) hash = 27;
 #ifdef DEBUG
     StringHasher hasher(2, seed);
     hasher.AddCharacter(c1);
     hasher.AddCharacter(c2);
     // If this assert fails then we failed to reproduce the two-character
     // version of the string hashing algorithm above.  One reason could be
     // that we were passed two digits as characters, since the hash
     // algorithm is different in that case.
     ASSERT_EQ(static_cast<int>(hasher.GetHash()), static_cast<int>(hash));
 #endif
@@ skipping 1140 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single break point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 } }  // namespace v8::internal