Added a few sanity-assertions about flat strings underlying buffers.

src/objects.cc

 // Copyright 2006-2008 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 600 matching lines @@
       String* buf = ss->buffer();
       ASSERT(!buf->IsSlicedString());
       Object* ok = buf->TryFlatten();
       if (ok->IsFailure()) return ok;
       // Under certain circumstances (TryFlattenIfNotFlat fails in
       // String::Slice) we can have a cons string under a slice.
       // In this case we need to get the flat string out of the cons!
       if (StringShape(String::cast(ok)).IsCons()) {
         ss->set_buffer(ConsString::cast(ok)->first());
       }
+      ASSERT(StringShape(this).IsAsciiRepresentation() ==
+          StringShape(ss->buffer()).IsAsciiRepresentation());
       return this;
     }
     case kConsStringTag: {
       ConsString* cs = ConsString::cast(this);
       if (cs->second()->length() == 0) {
         return this;
       }
       // There's little point in putting the flat string in new space if the
       // cons string is in old space.  It can never get GCed until there is
       // an old space GC.
@@ skipping 6744 matching lines @@
   // No break point.
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 
 
 } }  // namespace v8::internal