[turbofan] Introduce CommonOperatorReducer.

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.
 
 # Because standalone V8 builds are not supported, assume this is part of a
 # Chromium build.
 import("//build/module_args/v8.gni")
 
 # TODO(jochen): These will need to be user-settable to support standalone V8
 # builds.
@@ skipping 472 matching lines @@
     "src/compiler/ast-loop-assignment-analyzer.cc",
     "src/compiler/ast-loop-assignment-analyzer.h",
     "src/compiler/basic-block-instrumentor.cc",
     "src/compiler/basic-block-instrumentor.h",
     "src/compiler/change-lowering.cc",
     "src/compiler/change-lowering.h",
     "src/compiler/code-generator-impl.h",
     "src/compiler/code-generator.cc",
     "src/compiler/code-generator.h",
     "src/compiler/common-node-cache.h",
+    "src/compiler/common-operator-reducer.cc",
+    "src/compiler/common-operator-reducer.h",
     "src/compiler/common-operator.cc",
     "src/compiler/common-operator.h",
     "src/compiler/control-builders.cc",
     "src/compiler/control-builders.h",
     "src/compiler/control-equivalence.h",
     "src/compiler/control-reducer.cc",
     "src/compiler/control-reducer.h",
     "src/compiler/diamond.h",
     "src/compiler/frame.h",
     "src/compiler/gap-resolver.cc",
@@ skipping 952 matching lines @@
     deps = [
       ":v8_base",
       ":v8_nosnapshot",
     ]
   }
 
   direct_dependent_configs = [ ":external_config" ]
 }
 
 }