add interceptors which do not mask existing properties

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 30 matching lines @@
     // Set state_ to BEFORE_PROPERTY to ensure that the next lookup will be a
     // PROPERTY lookup.
     BEFORE_PROPERTY = INTERCEPTOR
   };
 
   LookupIterator(Handle<Object> receiver, Handle<Name> name,
                  Configuration configuration = PROTOTYPE_CHAIN)
       : configuration_(ComputeConfiguration(configuration, name)),
         state_(NOT_FOUND),
         exotic_index_state_(ExoticIndexState::kUninitialized),
+        interceptor_state_(InterceptorState::kUninitialized),
         property_details_(PropertyDetails::Empty()),
         isolate_(name->GetIsolate()),
         name_(name),
         receiver_(receiver),
+        holder_(GetRoot(receiver_, isolate_)),
+        holder_map_(holder_->map(), isolate_),
+        initial_holder_(holder_),
         number_(DescriptorArray::kNotFound) {
-    holder_ = GetRoot();
-    holder_map_ = handle(holder_->map(), isolate_);
     Next();
   }
 
   LookupIterator(Handle<Object> receiver, Handle<Name> name,
                  Handle<JSReceiver> holder,
                  Configuration configuration = PROTOTYPE_CHAIN)
       : configuration_(ComputeConfiguration(configuration, name)),
         state_(NOT_FOUND),
         exotic_index_state_(ExoticIndexState::kUninitialized),
+        interceptor_state_(InterceptorState::kUninitialized),
         property_details_(PropertyDetails::Empty()),
         isolate_(name->GetIsolate()),
         name_(name),
-        holder_map_(holder->map(), isolate_),
         receiver_(receiver),
         holder_(holder),
+        holder_map_(holder_->map(), isolate_),
+        initial_holder_(holder_),
         number_(DescriptorArray::kNotFound) {
     Next();
   }
 
   Isolate* isolate() const { return isolate_; }
   State state() const { return state_; }
   Handle<Name> name() const { return name_; }
 
   bool IsFound() const { return state_ != NOT_FOUND; }
   void Next();
   void NotFound() {
     has_property_ = false;
     state_ = NOT_FOUND;
   }
 
   Factory* factory() const { return isolate_->factory(); }
   Handle<Object> GetReceiver() const { return receiver_; }
   Handle<JSObject> GetStoreTarget() const;
   bool is_dictionary_holder() const { return holder_map_->is_dictionary_map(); }
   Handle<Map> transition_map() const {
     DCHECK_EQ(TRANSITION, state_);
     return Handle<Map>::cast(transition_);
   }
   template <class T>
   Handle<T> GetHolder() const {
     DCHECK(IsFound());
     return Handle<T>::cast(holder_);
   }
-  Handle<JSReceiver> GetRoot() const;
+  static Handle<JSReceiver> GetRoot(Handle<Object> receiver, Isolate* isolate);
   bool HolderIsReceiverOrHiddenPrototype() const;
 
   /* ACCESS_CHECK */
   bool HasAccess() const;
 
   /* PROPERTY */
   void PrepareForDataProperty(Handle<Object> value);
   void PrepareTransitionToDataProperty(Handle<Object> value,
                                        PropertyAttributes attributes,
                                        Object::StoreFromKeyed store_mode);
@@ skipping 27 matching lines @@
     return Handle<PropertyCell>::cast(transition_);
   }
   Handle<Object> GetAccessors() const;
   Handle<Object> GetDataValue() const;
   // Usually returns the value that was passed in, but may perform
   // non-observable modifications on it, such as internalize strings.
   Handle<Object> WriteDataValue(Handle<Object> value);
   void InternalizeName();
 
  private:
+  enum class InterceptorState {
+    kUninitialized,
+    kSkipNonMasking,
+    kProcessNonMasking
+  };
+
   Handle<Map> GetReceiverMap() const;
 
   MUST_USE_RESULT inline JSReceiver* NextHolder(Map* map);
   inline State LookupInHolder(Map* map, JSReceiver* holder);
+  void RestartLookupForNonMaskingInterceptors();
+  State LookupNonMaskingInterceptorInHolder(Map* map, JSReceiver* holder);
   Handle<Object> FetchValue() const;
   void ReloadPropertyInformation();
+  bool SkipInterceptor(JSObject* holder);
 
   bool IsBootstrapping() const;
 
   bool check_hidden() const { return (configuration_ & kHidden) != 0; }
   bool check_interceptor() const {
     return !IsBootstrapping() && (configuration_ & kInterceptor) != 0;
   }
   bool check_prototype_chain() const {
     return (configuration_ & kPrototypeChain) != 0;
   }
@@ skipping 16 matching lines @@
     } else {
       return configuration;
     }
   }
 
   enum class ExoticIndexState { kUninitialized, kNoIndex, kIndex };
   bool IsIntegerIndexedExotic(JSReceiver* holder);
 
   // If configuration_ becomes mutable, update
   // HolderIsReceiverOrHiddenPrototype.
-  Configuration configuration_;
+  const Configuration configuration_;
   State state_;
   bool has_property_;
   ExoticIndexState exotic_index_state_;
+  InterceptorState interceptor_state_;
   PropertyDetails property_details_;
-  Isolate* isolate_;
+  Isolate* const isolate_;
   Handle<Name> name_;
+  Handle<Object> transition_;
+  const Handle<Object> receiver_;
+  Handle<JSReceiver> holder_;
   Handle<Map> holder_map_;
-  Handle<Object> transition_;
-  Handle<Object> receiver_;
-  Handle<JSReceiver> holder_;
-
+  const Handle<JSReceiver> initial_holder_;
   int number_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LOOKUP_H_