[turbofan] Revive the useful parts of the SimplifiedOperatorReducer.

BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
 
 # Because standalone V8 builds are not supported, assume this is part of a
 # Chromium build.
@@ skipping 714 matching lines @@
     "src/compiler/register-configuration.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/state-values-utils.cc",
     "src/compiler/state-values-utils.h",
     "src/compiler/tail-call-optimization.cc",
     "src/compiler/tail-call-optimization.h",
     "src/compiler/typer.cc",
     "src/compiler/typer.h",
@@ skipping 936 matching lines @@
       sources += [
         "src/d8-debug.cc",
         "$target_gen_dir/d8-js.cc",
       ]
     }
     if (v8_enable_i18n_support) {
       deps += [ "//third_party/icu" ]
     }
   }
 }