[turbofan] Implement simplistic checkpoint 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 823 matching lines @@
     "src/compiler/ast-loop-assignment-analyzer.h",
     "src/compiler/basic-block-instrumentor.cc",
     "src/compiler/basic-block-instrumentor.h",
     "src/compiler/branch-elimination.cc",
     "src/compiler/branch-elimination.h",
     "src/compiler/bytecode-branch-analysis.cc",
     "src/compiler/bytecode-branch-analysis.h",
     "src/compiler/bytecode-graph-builder.cc",
     "src/compiler/bytecode-graph-builder.h",
     "src/compiler/c-linkage.cc",
+    "src/compiler/checkpoint-elimination.cc",
+    "src/compiler/checkpoint-elimination.h",
     "src/compiler/coalesced-live-ranges.cc",
     "src/compiler/coalesced-live-ranges.h",
     "src/compiler/code-assembler.cc",
     "src/compiler/code-assembler.h",
     "src/compiler/code-generator-impl.h",
     "src/compiler/code-generator.cc",
     "src/compiler/code-generator.h",
     "src/compiler/common-node-cache.cc",
     "src/compiler/common-node-cache.h",
     "src/compiler/common-operator-reducer.cc",
@@ skipping 1347 matching lines @@
   sources = [
     "test/fuzzer/wasm-asmjs.cc",
   ]
 
   deps = [
     ":fuzzer_support",
   ]
 
   configs = [ ":internal_config" ]
 }