Revert preparser duplicate detection.

src/SConscript

 # 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 214 matching lines @@
   'mode:debug': [
     'objects-debug.cc', 'prettyprinter.cc', 'regexp-macro-assembler-tracer.cc'
   ]
 }
 
 
 PREPARSER_SOURCES = {
   'all': Split("""
     allocation.cc
     bignum.cc
-    bignum-dtoa.cc
     cached-powers.cc
     conversions.cc
-    diy-fp.cc
-    dtoa.cc
-    fast-dtoa.cc
-    fixed-dtoa.cc
     hashmap.cc
     preparse-data.cc
     preparser.cc
     preparser-api.cc
     scanner-base.cc
     strtod.cc
     token.cc
     unicode.cc
     utils.cc
     """)
@@ skipping 130 matching lines @@
       snapshot_cc = 'snapshot.cc'
     snapshot_obj = context.ConfigureObject(env, snapshot_cc, CPPPATH=['.'])
   else:
     snapshot_obj = empty_snapshot_obj
   library_objs = [non_snapshot_files, libraries_obj, experimental_libraries_obj, snapshot_obj]
   return (library_objs, d8_objs, [mksnapshot], preparser_objs)
 
 
 (library_objs, d8_objs, mksnapshot, preparser_objs) = ConfigureObjectFiles()
 Return('library_objs d8_objs mksnapshot preparser_objs')