fix Set::AsArray to not leave undefined holes in output array

src/api.cc

 // Copyright 2012 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/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 6475 matching lines @@
 }
 
 
 Local<Array> Set::AsArray() const {
   i::Handle<i::JSSet> obj = Utils::OpenHandle(this);
   i::Isolate* isolate = obj->GetIsolate();
   i::Factory* factory = isolate->factory();
   LOG_API(isolate, "Set::AsArray");
   ENTER_V8(isolate);
   i::Handle<i::OrderedHashSet> table(i::OrderedHashSet::cast(obj->table()));
+  int capacity = table->UsedCapacity();
   int length = table->NumberOfElements();
   i::Handle<i::FixedArray> result = factory->NewFixedArray(length);
-  for (int i = 0; i < length; ++i) {
+  int result_index = 0;
+  for (int i = 0; i < capacity; ++i) {
     i::Object* key = table->KeyAt(i);
     if (!key->IsTheHole()) {
-      result->set(i, key);
+      result->set(result_index++, key);
     }
   }
+  DCHECK_EQ(result_index, result->length());
+  DCHECK_EQ(result_index, length);
   i::Handle<i::JSArray> result_array =
       factory->NewJSArrayWithElements(result, i::FAST_ELEMENTS, length);
   return Utils::ToLocal(result_array);
 }
 
 
 MaybeLocal<Promise::Resolver> Promise::Resolver::New(Local<Context> context) {
   PREPARE_FOR_EXECUTION(context, "Promise::Resolver::New", Resolver);
   i::Handle<i::Object> result;
   has_pending_exception =
@@ skipping 2335 matching lines @@
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 }  // namespace internal
 }  // namespace v8