In fact macros work in Firefox, the issue is just the way Firefox works with decoding URLs. Chrome doesn't decode the string dashboard URI for you and therefore you get:
http://myserver.com/apps/my_app#%2Fgdc%2Fmd%2FGoodSalesDemo%2Fobj%2F1952/85f6945b672d
Firefox does the decoding for you and you get
http://myserver.com/apps/my_app#/gdc/md/GoodSalesDemo/obj/1952/85f6945b672d
Therefore slash isn't a good character to separate %CURRENT_DASHBOARD_URI% and %CURRENT_DASHBOARD_TAB_URI% in your app.
Also when parsing the parameters out of the URL, you have to make sure that it's decoded - e.g. the decodeURIComponent function in JavaScript. decoding won't hurt the already decoded string in Firefox and will decode the string in Chrome.