Add a QJSManagedValue

A QJSManagedValue is a view on a QJSValue which always knows the engine
the value belongs to. This allows us to implement the JavaScript
semantics of the various QJSValue methods in a much more rigorous way.

[ChangeLog][QtQml] The new QJSManagedValue should be used instead of
QJSValue for manipulating properties and prototypes of JavaScript
values, as well as for calling JavaScript functions.

Change-Id: I9d445ffcf68dfa72dba9bae0818e83c80665ad66
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/qml/jsapi/qjsprimitivevalue.h b/src/qml/jsapi/qjsprimitivevalue.h
index 1a12104a61..27f38aec93 100644
--- a/src/qml/jsapi/qjsprimitivevalue.h
+++ b/src/qml/jsapi/qjsprimitivevalue.h
@@ -439,6 +439,7 @@ public:
     }
 
 private:
+    friend class QJSManagedValue;
     friend class QJSValue;
 
     constexpr bool asBoolean() const { return std::get<bool>(d); }