Fix internal issue #
1898791 ("PlatformAddressFactory PlatformAddress cache
causes memory to not be freed in a timely manner.").
The change makes the two PlatformAddressFactory.alloc() methods always
allocate separate PlatformAddress objects instead of looking for them
in the cache. This means that, should they have auto-free turned on,
there won't be a reference in the cache that prevents the freeing from
happening. And since we're talking about freshly-allocated memory anyway,
it would be surprising that either a matching address would be found in
cache *or* that a subsequent call to on() would ever happen with the
same address. So, it's a win on several fronts.