[json] replace remaining json.js code with C++ builtins.

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 341 matching lines @@
     "src/third_party/fdlibm/fdlibm.js",
     "src/js/regexp.js",
     "src/js/arraybuffer.js",
     "src/js/typedarray.js",
     "src/js/iterator-prototype.js",
     "src/js/collection.js",
     "src/js/weak-collection.js",
     "src/js/collection-iterator.js",
     "src/js/promise.js",
     "src/js/messages.js",
-    "src/js/json.js",
     "src/js/array-iterator.js",
     "src/js/string-iterator.js",
     "src/js/templates.js",
     "src/js/spread.js",
     "src/js/proxy.js",
     "src/debug/mirrors.js",
     "src/debug/debug.js",
     "src/debug/liveedit.js",
   ]
 
@@ skipping 1009 matching lines @@
     "src/runtime/runtime-compiler.cc",
     "src/runtime/runtime-date.cc",
     "src/runtime/runtime-debug.cc",
     "src/runtime/runtime-forin.cc",
     "src/runtime/runtime-function.cc",
     "src/runtime/runtime-futex.cc",
     "src/runtime/runtime-generator.cc",
     "src/runtime/runtime-i18n.cc",
     "src/runtime/runtime-internal.cc",
     "src/runtime/runtime-interpreter.cc",
-    "src/runtime/runtime-json.cc",
     "src/runtime/runtime-literals.cc",
     "src/runtime/runtime-liveedit.cc",
     "src/runtime/runtime-maths.cc",
     "src/runtime/runtime-numbers.cc",
     "src/runtime/runtime-object.cc",
     "src/runtime/runtime-operators.cc",
     "src/runtime/runtime-proxy.cc",
     "src/runtime/runtime-regexp.cc",
     "src/runtime/runtime-scopes.cc",
     "src/runtime/runtime-simd.cc",
@@ skipping 826 matching lines @@
   sources = [
     "test/fuzzer/wasm-asmjs.cc",
   ]
 
   deps = [
     ":fuzzer_support",
   ]
 
   configs = [ ":internal_config" ]
 }