[Bug 17974] appcache: Add an API to make appcache support caching specific URLs dynamically (and/or a JS "server" or "interceptor" for uncached resources?)
[Bug 18033] each MessageChannel acts as its own task source. This means that messages sent using this function are not guaranteed to execute in order, since the order task sources are processed isn't specified.
[Bug 18080] "This specification introduces two related mechanisms, similar to HTTP session cookies, for storing structured data on the client side." - structured data is no longer supported