[JSON] implement indentation in the BasicJsonStringifier and expose via API.

src/runtime/runtime-object.cc

 // Copyright 2014 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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
@@ skipping 209 matching lines @@
   LookupIterator it =
       LookupIterator::PropertyOrElement(isolate, object, key, &success);
   if (!success) return MaybeHandle<Object>();
 
   MAYBE_RETURN_NULL(Object::SetProperty(&it, value, language_mode,
                                         Object::MAY_BE_STORE_FROM_KEYED));
   return value;
 }
 
 MaybeHandle<Object> Runtime::BasicJsonStringify(Isolate* isolate,
-                                                Handle<Object> object) {
-  return BasicJsonStringifier(isolate).Stringify(object);
+                                                Handle<Object> object,
+                                                Handle<String> gap) {
+  return BasicJsonStringifier(isolate, gap).Stringify(object);
 }
 
 MaybeHandle<Object> Runtime::BasicJsonStringifyString(Isolate* isolate,
                                                       Handle<String> string) {
   return BasicJsonStringifier::StringifyString(isolate, string);
 }
 
 RUNTIME_FUNCTION(Runtime_GetPrototype) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
@@ skipping 786 matching lines @@
       isolate, o, key, &success, LookupIterator::OWN);
   if (!success) return isolate->heap()->exception();
   MAYBE_RETURN(
       JSReceiver::CreateDataProperty(&it, value, Object::THROW_ON_ERROR),
       isolate->heap()->exception());
   return *value;
 }
 
 }  // namespace internal
 }  // namespace v8