Arabic web-font Mark feature bug in Safari

Hello,

I've stumbled upon a bug in Safari (and webkit browsers) when using the Mark feature in web fonts,
As demonstrated by the screenshot, when a word has diacritics either on the beginning or the ending, the word space gets omitted.

I've tried my own fonts, and multiples fonts by other vendors but i get the same result, Only fonts that implement the Mark feature display the error.
Is anyone else facing the same problem?

Tested on Safari 6.0.5/osx 10.8.5