[json] handle proxies in BasicJsonSerializer.

src/objects.cc

 // Copyright 2015 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/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <sstream>
 
@@ skipping 701 matching lines @@
   // 3. If Type(obj) is not Object, throw a TypeError exception.
   if (!object->IsJSReceiver()) {
     THROW_NEW_ERROR(isolate,
                     NewTypeError(MessageTemplate::kCalledOnNonObject,
                                  isolate->factory()->NewStringFromAsciiChecked(
                                      "CreateListFromArrayLike")),
                     FixedArray);
   }
   // 4. Let len be ? ToLength(? Get(obj, "length")).
   Handle<JSReceiver> receiver = Handle<JSReceiver>::cast(object);
-  Handle<Object> raw_length_obj;
-  ASSIGN_RETURN_ON_EXCEPTION(
-      isolate, raw_length_obj,
-      JSReceiver::GetProperty(receiver, isolate->factory()->length_string()),
-      FixedArray);
   Handle<Object> raw_length_number;
   ASSIGN_RETURN_ON_EXCEPTION(isolate, raw_length_number,
-                             Object::ToLength(isolate, raw_length_obj),
+                             Object::GetLengthFromArrayLike(isolate, receiver),
                              FixedArray);
   uint32_t len;
   if (!raw_length_number->ToUint32(&len) ||
       len > static_cast<uint32_t>(FixedArray::kMaxLength)) {
     THROW_NEW_ERROR(isolate,
                     NewRangeError(MessageTemplate::kInvalidArrayLength),
                     FixedArray);
   }
   // 5. Let list be an empty List.
   Handle<FixedArray> list = isolate->factory()->NewFixedArray(len);
@@ skipping 26 matching lines @@
     }
     list->set(index, *next);
     // 7e. Set index to index + 1. (See loop header.)
   }
   // 8. Return list.
   return list;
 }
 
 
 // static
+MaybeHandle<Object> Object::GetLengthFromArrayLike(Isolate* isolate,
+                                                   Handle<Object> object) {
+  Handle<Object> val;
+  Handle<Object> key = isolate->factory()->length_string();

[Camillo Bruni, 2016/05/20 09:55:55]

I hope this is obvious enough that this is too slow to be used with JSArrays ;)

[Yang, 2016/05/20 12:47:18]

Unfortunately this is actually being used for JSArrays, when called from
Object::CreateListFromArrayLike. If you want, I can work on a separate CL to add
a fast path for JSArrays here...

+  ASSIGN_RETURN_ON_EXCEPTION(
+      isolate, val, Runtime::GetObjectProperty(isolate, object, key), Object);
+  return Object::ToLength(isolate, val);
+}
+
+// static
 Maybe<bool> JSReceiver::HasProperty(LookupIterator* it) {
   for (; it->IsFound(); it->Next()) {
     switch (it->state()) {
       case LookupIterator::NOT_FOUND:
       case LookupIterator::TRANSITION:
         UNREACHABLE();
       case LookupIterator::JSPROXY:
         return JSProxy::HasProperty(it->isolate(), it->GetHolder<JSProxy>(),
                                     it->GetName());
       case LookupIterator::INTERCEPTOR: {
@@ skipping 17602 matching lines @@
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 
 }  // namespace internal
 }  // namespace v8