[turbofan] Get rid of overly abstract SimplifiedGraphBuilder.

test/cctest/cctest.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 31 matching lines @@
       'include_dirs': [
         '../..',
       ],
       'sources': [  ### gcmole(all) ###
         '<(generated_file)',
         'compiler/c-signature.h',
         'compiler/codegen-tester.cc',
         'compiler/codegen-tester.h',
         'compiler/function-tester.h',
         'compiler/graph-builder-tester.h',
-        'compiler/simplified-graph-builder.cc',
-        'compiler/simplified-graph-builder.h',
         'compiler/test-basic-block-profiler.cc',
         'compiler/test-branch-combine.cc',
         'compiler/test-changes-lowering.cc',
         'compiler/test-gap-resolver.cc',
         'compiler/test-graph-visualizer.cc',
         'compiler/test-instruction.cc',
         'compiler/test-js-context-specialization.cc',
         'compiler/test-js-constant-cache.cc',
         'compiler/test-js-typed-lowering.cc',
         'compiler/test-jump-threading.cc',
@@ skipping 245 matching lines @@
             '../../tools/js2c.py',
             '<@(_outputs)',
             'TEST',  # type
             '<@(file_list)',
           ],
         }
       ],
     },
   ],
 }