Introduce NonJSProxyHolder returning Handle<JSObject> and return Handle<JSReceiver> for GetHolder

src/lookup.h

 // 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.
 
 #ifndef V8_LOOKUP_H_
 #define V8_LOOKUP_H_
 
 #include "src/factory.h"
 #include "src/isolate.h"
 #include "src/objects.h"
@@ skipping 75 matching lines @@
 
   bool IsFound() const { return state_ != NOT_FOUND; }
   void Next();
 
   Heap* heap() const { return isolate_->heap(); }
   Factory* factory() const { return isolate_->factory(); }
   Handle<Object> GetReceiver() const {
     return Handle<Object>::cast(maybe_receiver_.ToHandleChecked());
   }
   Handle<Map> holder_map() const { return holder_map_; }
-  Handle<JSObject> GetHolder() const {
+  Handle<JSReceiver> GetHolder() const {
+    ASSERT(IsFound());
+    return maybe_holder_.ToHandleChecked();
+  }
+  Handle<JSObject> GetNonJSProxyHolder() const {

[rossberg, 2014/07/24 11:18:32]

You should call it GetJSObjectHolder.

But I'm not sure I like such random downcast accessors all that much. How about
changing GetHolder to

template<class T>
Handle<T> GetHolder() const {
  ASSERT(IsFound());
  return Handle<T>::cast(maybe_holder_.ToHandleChecked());
}

     ASSERT(IsFound() && state_ != JSPROXY);
     return Handle<JSObject>::cast(maybe_holder_.ToHandleChecked());
   }
   Handle<JSReceiver> GetRoot() const;
   bool HolderIsReceiver() const;
 
   /* Dynamically reduce the trapped types. */
   void skip_interceptor() {
     configuration_ = static_cast<Configuration>(
         configuration_ & ~CHECK_INTERCEPTOR);
@@ skipping 80 matching lines @@
   MaybeHandle<Object> maybe_receiver_;
   MaybeHandle<JSReceiver> maybe_holder_;
 
   int number_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LOOKUP_H_