I had/have this same problem. No sound in Safari on a iPad 2 running 8.2. But sound was fine using the chrome browser on the same iPad.
The "no sound in iOS" was also happening with the Intel XDK mobile tester.
I tried some experiments.
I took an older version of the game, because I remembered at one point the sound WAS working in Safari before and sure enough it was fine.
Without getting into all the steps I took to get it to work, here is what seems to work (which is more of a hack).
For me it seemed to be music specific. If I get the music to work all the other sounds in the game seemed to function normally.
I re added/installed the music file using a wav file with a slightly different name(PCM, sterio,16 bit, 44,100Hz).
I made a iOS specific music function were I play the new music file at the same point the old file plays at, then I immediately stop it.
Just replacing the old music file doesn't seem to work.
It's like all it needs is for the sound to be activated/initialized, then everything is fine. This makes all the other sounds in the game work as they should. Including the old music file.
I don't know if you were saying you tried something like this already. Worked for me, I hope it will help you too.