[turbofan] Introduces a step to verify the machine graph.

src/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 644 matching lines @@
         'compiler/loop-analysis.cc',
         'compiler/loop-analysis.h',
         'compiler/loop-peeling.cc',
         'compiler/loop-peeling.h',
         'compiler/loop-variable-optimizer.cc',
         'compiler/loop-variable-optimizer.h',
         'compiler/machine-operator-reducer.cc',
         'compiler/machine-operator-reducer.h',
         'compiler/machine-operator.cc',
         'compiler/machine-operator.h',
+        'compiler/machine-graph-verifier.cc',
+        'compiler/machine-graph-verifier.h',
         'compiler/memory-optimizer.cc',
         'compiler/memory-optimizer.h',
         'compiler/move-optimizer.cc',
         'compiler/move-optimizer.h',
         'compiler/node-aux-data.h',
         'compiler/node-cache.cc',
         'compiler/node-cache.h',
         'compiler/node-marker.cc',
         'compiler/node-marker.h',
         'compiler/node-matchers.cc',
@@ skipping 1764 matching lines @@
       'conditions': [
         ['want_separate_host_toolset_mkpeephole==1', {
           'toolsets': ['host'],
         }, {
           'toolsets': ['target'],
         }],
       ],
     },
   ],
 }