Reland "Return MaybeHandle from NewConsString."

src/handles.h

 // 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 19 matching lines @@
 
 #include "allocation.h"
 #include "objects.h"
 
 namespace v8 {
 namespace internal {
 
 // A Handle can be converted into a MaybeHandle. Converting a MaybeHandle
 // into a Handle requires checking that it does not point to NULL.  This
 // ensures NULL checks before use.
+// Do not use MaybeHandle as argument type.
 
 template<typename T>
 class MaybeHandle {
  public:
   INLINE(MaybeHandle()) : location_(NULL) { }
 
   // Constructor for handling automatic up casting from Handle.
   // Ex. Handle<JSArray> can be passed when MaybeHandle<Object> is expected.
   template <class S> MaybeHandle(Handle<S> handle) {
 #ifdef DEBUG
@@ skipping 329 matching lines @@
 
   void Initialize() {
     next = limit = NULL;
     level = 0;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_H_