Allow embedder to set promise internal field count

src/factory.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/factory.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast.h"
 #include "src/base/bits.h"
@@ skipping 909 matching lines @@
   Handle<JSFunction> constructor(
       isolate()->native_context()->promise_function(), isolate());
   DCHECK(constructor->has_initial_map());
   Handle<Map> map(constructor->initial_map(), isolate());
 
   DCHECK(!map->is_prototype_map());
   Handle<JSObject> promise_obj = NewJSObjectFromMap(map);
   Handle<JSPromise> promise = Handle<JSPromise>::cast(promise_obj);
   promise->set_status(v8::Promise::kPending);
   promise->set_flags(0);
+  for (int i = 0; i < v8::Promise::kEmbedderFieldCount; i++) {
+    promise->SetEmbedderField(i, Smi::kZero);
+  }
 
   isolate()->RunPromiseHook(PromiseHookType::kInit, promise, undefined_value());
   return promise;
 }
 
 Handle<Context> Factory::NewNativeContext() {
   Handle<FixedArray> array =
       NewFixedArray(Context::NATIVE_CONTEXT_SLOTS, TENURED);
   array->set_map_no_write_barrier(*native_context_map());
   Handle<Context> context = Handle<Context>::cast(array);
@@ skipping 2012 matching lines @@
     Handle<AccessorInfo> prototype =
         Accessors::FunctionPrototypeInfo(isolate(), rw_attribs);
     Descriptor d = Descriptor::AccessorConstant(
         Handle<Name>(Name::cast(prototype->name())), prototype, rw_attribs);
     map->AppendDescriptor(&d);
   }
 }
 
 }  // namespace internal
 }  // namespace v8