Avoid "unload" to preserve page back/forward cache

[jakearchibald]

Add an unload listener

rsvp.js/lib/rsvp/asap.js

Line 18 in 7933854

window.addEventListener('unload', function(){

breaks the back/forward page cache.

The Chrome bug was closed almost a year ago now, it's probably save to remove right?

Failing that, switch to postMessage? https://github.com/NobleJS/setImmediate/blob/6dd6a2dd3162f15848ca4d609d70b778b9b59261/setImmediate.js#L124

(issue spotted by @tobie‎)

[stefanpenner]

@jakearchibald removing the fix is a good idea, do you have time for a PR?

the back/forward page cache issue seems like a bug unto itself?

PostMessage has many other issues: cujojs/when#197 (comment)

[jakearchibald]

The reason the back/forward page cache goes away with "unload" is:

1. User clicks link
2. Unload event fired
3. Unload listener does some teardown work
4. User clicks "back"
5. Previous page reshown very quickly in previous state, but it's broken because of the teardown stuff

[stefanpenner]

@jakearchibald ah.

Also, thanks again for the bug report and the subsequent PR.