Implement handlified String::Flatten.

src/objects-debug.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 504 matching lines @@
     SlicedString::cast(this)->SlicedStringVerify();
   }
 }
 
 
 void ConsString::ConsStringVerify() {
   CHECK(this->first()->IsString());
   CHECK(this->second() == GetHeap()->empty_string() ||
         this->second()->IsString());
   CHECK(this->length() >= ConsString::kMinLength);
+  CHECK(this->length() == this->first()->length() + this->second()->length());
   if (this->IsFlat()) {
     // A flat cons can only be created by String::SlowTryFlatten.
     // Afterwards, the first part may be externalized.
     CHECK(this->first()->IsSeqString() || this->first()->IsExternalString());
   }
 }
 
 
 void SlicedString::SlicedStringVerify() {
   CHECK(!this->parent()->IsConsString());
@@ skipping 645 matching lines @@
   for (int i = 0; i < number_of_transitions(); ++i) {
     if (!CheckOneBackPointer(current_map, GetTarget(i))) return false;
   }
   return true;
 }
 
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal