[whatwg] Image cache behaviour

[Andrew Oakley]

I've noticed that some browsers (Firefox, Opera, IE) cache images
without following the HTTP expiry rules.  This does not appear to be
permitted by the HTML5 specification.

I've got a test case for this (with explanation) here:
http://ado.is-a-geek.net/expired/tests/image_cache_test.html

Boris Zbarsky believes this behaviour is required for compatibility so
I think it is worth adding to HTML5.  This was discussed on the Mozilla
bug tracker here: https://bugzilla.mozilla.org/show_bug.cgi?id=295942

How do other browsers handle this?  It seems to be possible to get
Opera and IE to throw the image away by changing the src attribute on
the img.

Are there similar caches for any other type of object or is this just
images?