document.write and async

Follow each link and look at the console

• oldschool.html - This is a sync script, doc-writing another script. Both are loaded fine.
• async.html - This is the same initial script but loaded with async attribute. The second, doc-written script is blocked.
• snip.html - Same as above, only using the "async snippet", the pre-async way of async-loading scripts. Result: the second, doc-written script is still blocked.

Chrome blocks, FF blocks with a different message, Safari blocks with no message. Silent and deadly.