oncreate async, fixes #904

[m59peacemaker]

Just checking if the function is async and outputting async function if so, rather than just always only outputting function. The tests don't do anything but use await inside the function. If the async keyword is not present, using await in the function is a syntax error, so runtime tests will fail.

I also wrote tests for js/samples, but as the README says to avoid those and the runtime tests are sufficient, I am not including them unless you'd like me to.

[m59peacemaker]

Should I add the "skip ssr" option to the config for these tests?

[Conduitry]

I don't think it's the SSR that's the issue, it's the version of Node that's running the tests - version 6 which doesn't support async/await. I wasn't thinking about that complication when I suggested this method for testing... Not sure the best way to go forward here. It'd be nice not to write a js/samples test for this, as those are annoying to maintain. But only running unit tests on more recent versions of Node isn't great either, as there are certainly going to be people running Svelte under Node 4 and Node 6 for quite a while.

[m59peacemaker]

Hmm. Well, like I said, I have those js/samples tests ready to go if you decide that's preferable. Otherwise, let me know if I can help some other way to solve this.

[Conduitry]

c5943d7 Oh heh that's cute, and fairly obvious in hindsight

[Rich-Harris]

except i messed it up! needed to be [1], not [0]...

[Rich-Harris]

Right, all the tests are passing now. Thanks @m59peacemaker!

[m59peacemaker]

Glad to help!