[turbofan] Remove the JSContextRelaxation 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': ['../../build/toolchain.gypi', '../../build/features.gypi'],
   'targets': [
@@ skipping 43 matching lines @@
         'compiler/graph-reducer-unittest.cc',
         'compiler/graph-reducer-unittest.h',
         'compiler/graph-trimmer-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',
         'compiler/instruction-sequence-unittest.h',
         'compiler/js-builtin-reducer-unittest.cc',
-        'compiler/js-context-relaxation-unittest.cc',
         'compiler/js-create-lowering-unittest.cc',
         'compiler/js-intrinsic-lowering-unittest.cc',
         'compiler/js-operator-unittest.cc',
         'compiler/js-typed-lowering-unittest.cc',
         'compiler/linkage-tail-call-unittest.cc',
         'compiler/liveness-analyzer-unittest.cc',
         'compiler/live-range-unittest.cc',
         'compiler/load-elimination-unittest.cc',
         'compiler/loop-peeling-unittest.cc',
         'compiler/machine-operator-reducer-unittest.cc',
@@ skipping 121 matching lines @@
             '../../build/isolate.gypi',
           ],
           'sources': [
             'unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }