Improve SeqString::Truncate for latest allocated strings.

src/objects.h

 // 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 7736 matching lines @@
  public:
   // Casting.
   static inline SeqString* cast(Object* obj);
 
   // Layout description.
   static const int kHeaderSize = String::kSize;
 
   // Truncate the string in-place if possible and return the result.
   // In case of new_length == 0, the empty string is returned without
   // truncating the original string.
-  MUST_USE_RESULT String* Truncate(int new_length);
-
+  MUST_USE_RESULT static Handle<String> Truncate(Handle<SeqString> string,
+                                                 int new_length);
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(SeqString);
 };
 
 
 // The AsciiString class captures sequential ASCII string objects.
 // Each character in the AsciiString is an ASCII character.
 class SeqOneByteString: public SeqString {
  public:
   static const bool kHasAsciiEncoding = true;
@@ skipping 1492 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_