EEST
is not recognized as a valid time zone in this scenario. Any parenthesized versions are simply being disregarded, regardless of what they contain.
For instance (I reside in the Pacific time zone):
// Pacific, by default
new Date("Thu, 26 Jun 2014 09:09:27");
Thu Jun 26 2014 09:09:27 GMT-0700 (Pacific Daylight Time)
// Pacific, explicitly
new Date("Thu, 26 Jun 2014 09:09:27 PDT");
Thu Jun 26 2014 09:09:27 GMT-0700 (Pacific Daylight Time)
// Mountain, explicitly
new Date("Thu, 26 Jun 2014 09:09:27 MDT");
Thu Jun 26 2014 10:09:27 GMT-0700 (Pacific Daylight Time)
// Disregarded, defaults to Pacific
new Date("Thu, 26 Jun 2014 09:09:27 (MDT)");
Thu Jun 26 2014 09:09:27 GMT-0700 (Pacific Daylight Time)
new Date("Thu, 26 Jun 2014 09:09:27 (EEST)");
Thu Jun 26 2014 09:09:27 GMT-0700 (Pacific Daylight Time)