Dates can not be used as properties after js engine switch

Scenario

• get "Date" js object via the Probe;
• save it as a project/product/module property var;
• use it as a "Date" js object in Rule or somewhere else (e.g. calling "getFullYear()");

Expected behavior (prior to qbs 2.0)
Everything works, property can be used as [object Date]

Actual behavior (qbs 2.0)
Property has type [object Object], "not a function" error