[turbofan] Introduce representation-change.cc, move stuff there, minus dead code.

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 840 matching lines @@
     "src/compiler/pipeline.cc",
     "src/compiler/pipeline.h",
     "src/compiler/pipeline-statistics.cc",
     "src/compiler/pipeline-statistics.h",
     "src/compiler/raw-machine-assembler.cc",
     "src/compiler/raw-machine-assembler.h",
     "src/compiler/register-allocator.cc",
     "src/compiler/register-allocator.h",
     "src/compiler/register-allocator-verifier.cc",
     "src/compiler/register-allocator-verifier.h",
+    "src/compiler/representation-change.cc",
     "src/compiler/representation-change.h",
     "src/compiler/schedule.cc",
     "src/compiler/schedule.h",
     "src/compiler/scheduler.cc",
     "src/compiler/scheduler.h",
     "src/compiler/select-lowering.cc",
     "src/compiler/select-lowering.h",
     "src/compiler/simplified-lowering.cc",
     "src/compiler/simplified-lowering.h",
     "src/compiler/simplified-operator-reducer.cc",
@@ skipping 998 matching lines @@
     if (!is_component_build) {
       sources += [
         "$target_gen_dir/d8-js.cc",
       ]
     }
     if (v8_enable_i18n_support) {
       deps += [ "//third_party/icu" ]
     }
   }
 }