Javascript editor does not validate code after changes

[musienko-maxim]

1 Create javascript file and paste for example next code:
function myFunction(name,job) {
document.getElementById("demo").innerHTML ="Welcome " + name + ", the " + job + ".";
}
Expected result: we should see error marker with error 'document is undefined'
Actual result: The error marker does not appear
Close file and open again. Error marker appears. After applying 'quick fix' proposal - all work correct.