Googling has only shown me how to do it using chrome.
window.fbAsyncInit doesn't seem to be firing.
If I console.log(FB) after the page has loaded it's there, but it can't find variable 'FB' inside my main.js, so obviously its loading, but just not available to my script.
Same goes for trying to load AWS js sdk.
I think its worth mentioning, that this is a tumblr extension I'm working on.