RegExp replace with empty string optimization by Sandholm.

src/codegen.h

 // 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 402 matching lines @@
   Major MajorKey() { return Instanceof; }
   int MinorKey() { return 0; }
 };
 
 
 enum NegativeZeroHandling {
   kStrictNegativeZero,
   kIgnoreNegativeZero
 };
 
-  
+
 class GenericUnaryOpStub : public CodeStub {
  public:
   GenericUnaryOpStub(Token::Value op,
                      UnaryOverwriteMode overwrite,
                      NegativeZeroHandling negative_zero = kStrictNegativeZero)
       : op_(op), overwrite_(overwrite), negative_zero_(negative_zero) { }
 
  private:
   Token::Value op_;
   UnaryOverwriteMode overwrite_;
@@ skipping 437 matching lines @@
   StringCharFromCodeGenerator char_from_code_generator_;
 
   DISALLOW_COPY_AND_ASSIGN(StringCharAtGenerator);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CODEGEN_H_