Propagate not-found on proxy target to GetRealNamedProperty

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index c692671354a0763e82e5133a80649050e5c2fbc8..b07f3a3ad49335e1dfa0a55000fcad59ad8dcf61 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -9682,7 +9682,7 @@ class JSProxy: public JSReceiver {
   // ES6 9.5.8
   MUST_USE_RESULT static MaybeHandle<Object> GetProperty(
       Isolate* isolate, Handle<JSProxy> proxy, Handle<Name> name,
-      Handle<Object> receiver);
+      Handle<Object> receiver, bool* was_found);
 
   // ES6 9.5.9
   MUST_USE_RESULT static Maybe<bool> SetProperty(Handle<JSProxy> proxy,