Get rid of the NONEXISTENT PropertyType

src/property.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/property.h"
 
 #include "src/handles-inl.h"
 #include "src/ostreams.h"
 
 namespace v8 {
@@ skipping 29 matching lines @@
          << " -index = " << r.GetFieldIndex().property_index() << "\n"
          << " -field type:";
       r.GetFieldType()->PrintTo(os);
       return os << "\n";
     case CALLBACKS:
       return os << " -type = call backs\n";
     case HANDLER:
       return os << " -type = lookup proxy\n";
     case INTERCEPTOR:
       return os << " -type = lookup interceptor\n";
-    case NONEXISTENT:
-      UNREACHABLE();
-      break;
   }
   return os;
 }
 
 
 OStream& operator<<(OStream& os, const Descriptor& d) {
   return os << "Descriptor " << Brief(*d.GetKey()) << " @ "
             << Brief(*d.GetValue());
 }
 
 } }  // namespace v8::internal