WIP [esnext] implement async iteration proposal

src/objects-body-descriptors-inl.h

 // 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.
 
 #ifndef V8_OBJECTS_BODY_DESCRIPTORS_INL_H_
 #define V8_OBJECTS_BODY_DESCRIPTORS_INL_H_
 
 #include "src/objects-body-descriptors.h"
 
 namespace v8 {
@@ skipping 453 matching lines @@
       return ReturnType();
     case TRANSITION_ARRAY_TYPE:
       return Op::template apply<TransitionArray::BodyDescriptor>(p1, p2, p3);
     case JS_OBJECT_TYPE:
     case JS_ERROR_TYPE:
     case JS_ARGUMENTS_TYPE:
     case JS_PROMISE_CAPABILITY_TYPE:
     case JS_PROMISE_TYPE:
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
     case JS_GENERATOR_OBJECT_TYPE:
+    case JS_ASYNC_GENERATOR_OBJECT_TYPE:
+    case JS_ASYNC_FROM_SYNC_ITERATOR_TYPE:
     case JS_VALUE_TYPE:
     case JS_DATE_TYPE:
     case JS_ARRAY_TYPE:
     case JS_MODULE_NAMESPACE_TYPE:
     case JS_TYPED_ARRAY_TYPE:
     case JS_DATA_VIEW_TYPE:
     case JS_SET_TYPE:
     case JS_MAP_TYPE:
     case JS_SET_ITERATOR_TYPE:
     case JS_MAP_ITERATOR_TYPE:
@@ skipping 128 matching lines @@
 
 template <typename ObjectVisitor>
 void HeapObject::IterateBodyFast(InstanceType type, int object_size,
                                  ObjectVisitor* v) {
   BodyDescriptorApply<CallIterateBody, void>(type, this, object_size, v);
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_BODY_DESCRIPTORS_INL_H_