Fix a cornercase for instanceof

It's possible to define a getter function for the prototype
property of Function objects. Ensure this doesn't mess up
things by not taking shortcuts.

Change-Id: Id981f3080f5c5c0714a1b7b6de27b4af04e794c8
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/qml/jsruntime/qv4functionobject_p.h b/src/qml/jsruntime/qv4functionobject_p.h
index ba1146af37..a9ffa90b90 100644
--- a/src/qml/jsruntime/qv4functionobject_p.h
+++ b/src/qml/jsruntime/qv4functionobject_p.h
@@ -91,8 +91,6 @@ DECLARE_HEAP_OBJECT(FunctionObject, Object) {
 
     unsigned int formalParameterCount() { return function ? function->nFormals : 0; }
     unsigned int varCount() { return function ? function->compiledFunction->nLocals : 0; }
-
-    const QV4::Object *protoProperty() const { return propertyData(Index_Prototype)->as<QV4::Object>(); }
 };
 
 struct FunctionCtor : FunctionObject {
@@ -190,6 +188,9 @@ struct Q_QML_EXPORT FunctionObject: Object {
     bool isBinding() const;
     bool isBoundFunction() const;
 
+    ReturnedValue protoProperty() const { return get(engine()->id_prototype()); }
+
+
     QQmlSourceLocation sourceLocation() const;
 };