A function loaded and returned from a foreign context can't be called with new operator.

Test case:

var se = new javax.script.ScriptEngineManager();
var e = se.getEngineByName("nashorn");
e.eval("function doIt2(){}");
var b = e.getBindings(javax.script.ScriptContext.ENGINE_SCOPE);
for( k in b){
    new b[k]();
}