[turbofan] Introduce CommonOperatorReducer.

test/unittests/unittests.gyp

 # Copyright 2014 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'v8_code': 1,
   },
   'includes': ['../../build/toolchain.gypi', '../../build/features.gypi'],
   'targets': [
@@ skipping 20 matching lines @@
         'base/iterator-unittest.cc',
         'base/platform/condition-variable-unittest.cc',
         'base/platform/mutex-unittest.cc',
         'base/platform/platform-unittest.cc',
         'base/platform/semaphore-unittest.cc',
         'base/platform/time-unittest.cc',
         'base/sys-info-unittest.cc',
         'base/utils/random-number-generator-unittest.cc',
         'char-predicates-unittest.cc',
         'compiler/change-lowering-unittest.cc',
+        'compiler/common-operator-reducer-unittest.cc',
         'compiler/common-operator-unittest.cc',
         'compiler/compiler-test-utils.h',
         'compiler/control-equivalence-unittest.cc',
         'compiler/diamond-unittest.cc',
         'compiler/graph-reducer-unittest.cc',
         'compiler/graph-unittest.cc',
         'compiler/graph-unittest.h',
         'compiler/instruction-selector-unittest.cc',
         'compiler/instruction-selector-unittest.h',
         'compiler/instruction-sequence-unittest.cc',
@@ skipping 78 matching lines @@
           'direct_dependent_settings': {
             'cflags!': [
               '-pedantic',
             ],
           },
         }],
       ],
     },
   ],
 }