@fileoverview in file with async gets moved

[evmar]

Consider a file like:

/** @fileoverview foo */

codeHere();

If codeHere is export {}; async function ... or export async function ... the fileoverview comment transformer causes the fileoverview to be moved down below the goog.module etc in the emit.

But if instead it's async function ... or export function ... then it stays at the top!

It seems to be some interaction with the many weird things the fileoverview transformer does, along with maybe how export/async are downlevelled.

[evmar]

I tinkered a bit with some of the fileoverview transformer functions (e.g. we have code in there that links to bugs that have since been fixed) but nothing jumped out at me.

[brad4d]

Created Google internal issue http://b/142269197