Prepare GetProperty(Attributes)WithInterceptor to support elements

BUG=v8:4137
LOG=n

Review URL: https://codereview.chromium.org/1147863002

Cr-Commit-Position: refs/heads/master@{#28564}

src/lookup.h

@@ -126,7 +126,17 @@ class LookupIterator final BASE_EMBEDDED {
   Isolate* isolate() const { return isolate_; }
   State state() const { return state_; }
 
-  Handle<Name> name() const { return name_; }
+  Handle<Name> name() const {
+    DCHECK(!IsElement());
+    return name_;
+  }
+  Handle<Name> GetName() {
+    if (name_.is_null()) {
+      DCHECK(IsElement());
+      name_ = isolate_->factory()->Uint32ToString(index_);
+    }
+    return name_;
+  }
   uint32_t index() const { return index_; }
 
   bool IsElement() const { return index_ != kMaxUInt32; }

src/objects.h

@@ -1861,9 +1861,7 @@ class JSObject: public JSReceiver {
 
   // Used from JSReceiver.
   MUST_USE_RESULT static Maybe<PropertyAttributes>
-      GetPropertyAttributesWithInterceptor(Handle<JSObject> holder,
-                                           Handle<Object> receiver,
-                                           Handle<Name> name);
+  GetPropertyAttributesWithInterceptor(LookupIterator* it);
   MUST_USE_RESULT static Maybe<PropertyAttributes>
       GetPropertyAttributesWithFailedAccessCheck(LookupIterator* it);
   MUST_USE_RESULT static Maybe<PropertyAttributes>