[turbofan] Implement simplistic checkpoint reducer.

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': ['../../gypfiles/toolchain.gypi', '../../gypfiles/features.gypi'],
   'targets': [
@@ skipping 23 matching lines @@
         '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',
         'cancelable-tasks-unittest.cc',
         'char-predicates-unittest.cc',
         'compiler/branch-elimination-unittest.cc',
+        'compiler/checkpoint-elimination-unittest.cc',
         'compiler/coalesced-live-ranges-unittest.cc',
         'compiler/common-operator-reducer-unittest.cc',
         'compiler/common-operator-unittest.cc',
         'compiler/compiler-test-utils.h',
         'compiler/control-equivalence-unittest.cc',
         'compiler/control-flow-optimizer-unittest.cc',
         'compiler/dead-code-elimination-unittest.cc',
         'compiler/diamond-unittest.cc',
         'compiler/effect-control-linearizer-unittest.cc',
         'compiler/escape-analysis-unittest.cc',
@@ skipping 164 matching lines @@
             '../../gypfiles/isolate.gypi',
           ],
           'sources': [
             'unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }