[turbofan] Introduce separate SelectLowering reducer.

tools/gyp/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 471 matching lines @@
         '../../src/compiler/pipeline-statistics.h',
         '../../src/compiler/raw-machine-assembler.cc',
         '../../src/compiler/raw-machine-assembler.h',
         '../../src/compiler/register-allocator.cc',
         '../../src/compiler/register-allocator.h',
         '../../src/compiler/representation-change.h',
         '../../src/compiler/schedule.cc',
         '../../src/compiler/schedule.h',
         '../../src/compiler/scheduler.cc',
         '../../src/compiler/scheduler.h',
+        '../../src/compiler/select-lowering.cc',
+        '../../src/compiler/select-lowering.h',
         '../../src/compiler/simplified-lowering.cc',
         '../../src/compiler/simplified-lowering.h',
         '../../src/compiler/simplified-operator-reducer.cc',
         '../../src/compiler/simplified-operator-reducer.h',
         '../../src/compiler/simplified-operator.cc',
         '../../src/compiler/simplified-operator.h',
         '../../src/compiler/source-position.cc',
         '../../src/compiler/source-position.h',
         '../../src/compiler/typer.cc',
         '../../src/compiler/typer.h',
@@ skipping 1225 matching lines @@
         }],
         ['v8_compress_startup_data=="bz2"', {
           'libraries': [
             '-lbz2',
           ]
         }],
       ],
     },
   ],
 }