In-place shrinking of descriptor arrays with non-live transitions.

src/property.cc

 // 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 71 matching lines @@
       break;
     case INTERCEPTOR:
       PrintF(out, " -type = lookup interceptor\n");
       break;
     case CONSTANT_TRANSITION:
       PrintF(out, " -type = constant property transition\n");
       PrintF(out, " -map:\n");
       GetTransitionMap()->Print(out);
       PrintF(out, "\n");
       break;
-    case NULL_DESCRIPTOR:
-      PrintF(out, " =type = null descriptor\n");
+    case NONEXISTENT:
+      UNREACHABLE();
       break;
   }
 }
 
 
 void Descriptor::Print(FILE* out) {
   PrintF(out, "Descriptor ");
   GetKey()->ShortPrint(out);
   PrintF(out, " @ ");
   GetValue()->ShortPrint(out);
@@ skipping 12 matching lines @@
     case CALLBACKS: {
       if (!value_->IsAccessorPair()) return false;
       AccessorPair* accessors = AccessorPair::cast(value_);
       return accessors->getter()->IsMap() || accessors->setter()->IsMap();
     }
     case NORMAL:
     case FIELD:
     case CONSTANT_FUNCTION:
     case HANDLER:
     case INTERCEPTOR:
-    case NULL_DESCRIPTOR:
       return false;
+    case NONEXISTENT:
+      UNREACHABLE();
+      break;
   }
   UNREACHABLE();  // Keep the compiler happy.
   return false;
 }
 
 
 } }  // namespace v8::internal