[builtins] Move builtins into own files

src/builtins/builtins-json.cc

+// Copyright 2016 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.
+
+#include "src/builtins/builtins.h"
+#include "src/builtins/builtins-utils.h"
+
+#include "src/json-parser.h"
+#include "src/json-stringifier.h"
+
+namespace v8 {
+namespace internal {
+
+// ES6 section 24.3.1 JSON.parse.
+BUILTIN(JsonParse) {
+  HandleScope scope(isolate);
+  Handle<Object> source = args.atOrUndefined(isolate, 1);
+  Handle<Object> reviver = args.atOrUndefined(isolate, 2);
+  Handle<String> string;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, string,
+                                     Object::ToString(isolate, source));
+  string = String::Flatten(string);
+  RETURN_RESULT_OR_FAILURE(
+      isolate, string->IsSeqOneByteString()
+                   ? JsonParser<true>::Parse(isolate, string, reviver)
+                   : JsonParser<false>::Parse(isolate, string, reviver));
+}
+
+// ES6 section 24.3.2 JSON.stringify.
+BUILTIN(JsonStringify) {
+  HandleScope scope(isolate);
+  JsonStringifier stringifier(isolate);
+  Handle<Object> object = args.atOrUndefined(isolate, 1);
+  Handle<Object> replacer = args.atOrUndefined(isolate, 2);
+  Handle<Object> indent = args.atOrUndefined(isolate, 3);
+  RETURN_RESULT_OR_FAILURE(isolate,
+                           stringifier.Stringify(object, replacer, indent));
+}
+
+}  // namespace internal
+}  // namespace v8