disable mutation-observer scheduler in IE

[davedoran]

No description provided.

[benjamingr]

@davedoran hey - everything OK?

[davedoran]

Yeah - sorry; didn't mean to submit this PR back to the main fork.

[benjamingr]

@davedoran ok - if I may ask - why was it required on your end?

(You can setScheduler by the way and avoid changing the source code)

[davedoran]

I develop a large application that is migrating from jQuery to BlueBird. We're noticing that - on IE11 - the MutationObserver occasionally fails to trigger when it should. The result is (rarely) a serious performance impact on IE. We have seen delays in the range of minutes where the application is blocked waiting for the callback.

Unfortunately, I don't have a reliable testcase outside of my application (hence - not submitting this patch) but falling back to setTimeout on IE sidesteps the issue.

Thanks for the hint re: setScheduler. That will be very useful.

[benjamingr]

Thanks for the update, we'll look into it.

[davedoran]

Cool - thanks. I suspect we're hitting the same issue discussed here:

#1161
https://github.com/lowkay/MutationObserverSchedulerBug