[turbofan] Remove the JSContextRelaxation reducer.

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.
 
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 if (is_android) {
@@ skipping 771 matching lines @@
     "src/compiler/instruction-selector.cc",
     "src/compiler/instruction-selector.h",
     "src/compiler/instruction.cc",
     "src/compiler/instruction.h",
     "src/compiler/int64-lowering.cc",
     "src/compiler/int64-lowering.h",
     "src/compiler/js-builtin-reducer.cc",
     "src/compiler/js-builtin-reducer.h",
     "src/compiler/js-call-reducer.cc",
     "src/compiler/js-call-reducer.h",
-    "src/compiler/js-context-relaxation.cc",
-    "src/compiler/js-context-relaxation.h",
     "src/compiler/js-context-specialization.cc",
     "src/compiler/js-context-specialization.h",
     "src/compiler/js-create-lowering.cc",
     "src/compiler/js-create-lowering.h",
     "src/compiler/js-frame-specialization.cc",
     "src/compiler/js-frame-specialization.h",
     "src/compiler/js-generic-lowering.cc",
     "src/compiler/js-generic-lowering.h",
     "src/compiler/js-global-object-specialization.cc",
     "src/compiler/js-global-object-specialization.h",
@@ skipping 1188 matching lines @@
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [
     ":internal_config",
     ":features",
     ":toolchain",
   ]
 }