Bug 924125 - DataStore API is always returning empty objects, r=ehsan

--HG--
rename : dom/datastore/tests/test_basic.html => dom/datastore/tests/test_bug924104.html
Bug 924083 - Fix uninitialized mOldDesc in _OldCacheEntryWrapper(nsICacheEntryInfo*) ctor, r=michal
Bug 913814: Fix test_304_responses.js to not be dependent on random GC forcement, r=michal