d5cf33a798 adds a `yield` to bibliography.js, which runs in modal
windows (e.g., Create Bib), but there's a weird interaction between
Bluebird and modal dialogs that can result in hangs -- presumably
something to do with things being queued on the event loop but the modal
dialog preventing other code from running? This was breaking
bibliographyTest, but it seemed to work fine for me in normal usage,
waiting properly for a running styles initialization to finish. It's
possible this problem is limited to tests, but in the past, at least, I
apparently decided that this was a general problem with `yield` in modal
dialogs [1]. (See also: [2].) In any case, calling `yield
Zotero.Styles.init()` from the Create Bib window was hanging the test,
so for now do a synchronous check for style initialization to avoid it,
and we should make sure that `yield` actually works in other contexts.
[1] https://github.com/zotero/zotero/commit/99dd1c069776
[2] https://github.com/zotero/zotero/commit/c2dd531cec4
9b53570968