Test:

    <!DOCTYPE HTML>
    <script>document.write(atob('PG1ldGEgaHR0cC1lcXVpdj0iQ29udGVudC1UeXBlIiBjb250ZW50PSJ0ZXh0L2h0bWw7Y2hhcnNldD1JU08tODg1OS0xIj4='))</script>
    <script>document.write(atob('PG1ldGEgaHR0cC1lcXVpdj0iQ29udGVudC1UeXBlIiBjb250ZW50PSJ0ZXh0L2h0bWw7Y2hhcnNldD1JU08tODg1OS05Ij4='))</script>

Expected result: Windows-1252

Encoding used by browser is: Script did not run.

Result: Script did not run.