This important bit is missing.
AFAIK, there is no way to clear the cache using DOM. It’s available in Chrome on chrome://appcache-internals/ I don’t see any commands to clear appcache in the protocol, under ApplicationCache domain http://trac.webkit.org/browser/trunk/Source/WebCore/inspector/Inspector.json#L1423. I could implement UI part, but I need back-end part working.
<rdar://problem/19281660>