OS: Windows 7 Browsers: IE 11.0.9600 ; EDGE 38.14393
When setting the OS timezone to UTC + 3:00 (Istanbul), the returned timezone is Europe/Helsinki. This is great for the period when Helsinki is not in the daylight savings period, since the time zones have the same offset. But, since Turkey is a country that does not have daylight savings and Finland does, the timezone for Istanbul is not correct in the daylight savings period of Finland.
Firefox and Chrome work great, Only IE and EDGE have problems.