Separate DuplicateFinder from Scanner.

src/v8.gyp

 # 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 1021 matching lines @@
         'msan.h',
         'objects-body-descriptors-inl.h',
         'objects-body-descriptors.h',
         'objects-debug.cc',
         'objects-inl.h',
         'objects-printer.cc',
         'objects.cc',
         'objects.h',
         'ostreams.cc',
         'ostreams.h',
+        'parsing/duplicate-finder.cc',
+        'parsing/duplicate-finder.h',
         'parsing/expression-classifier.h',
         'parsing/func-name-inferrer.cc',
         'parsing/func-name-inferrer.h',
         'parsing/parameter-initializer-rewriter.cc',
         'parsing/parameter-initializer-rewriter.h',
         'parsing/parse-info.cc',
         'parsing/parse-info.h',
         'parsing/parser-base.h',
         'parsing/parser.cc',
         'parsing/parser.h',
@@ skipping 1358 matching lines @@
       'conditions': [
         ['want_separate_host_toolset_mkpeephole==1', {
           'toolsets': ['host'],
         }, {
           'toolsets': ['target'],
         }],
       ],
     },
   ],
 }