Dropdowns: key events are not propagated from inactive and disabled dropdowns

[luktom]

Hi,

key events are not propagated from dropdown when it is inactive or disabled.

Reduced test case on JS Bin: https://jsbin.com/hoharusisa there is ESC key handler attached to the document element.

1. Click on ESC - nothing happens.
2. Click on ESC - handler is invoked.

Event propagation is disabled in the https://github.com/twbs/bootstrap/blob/v4-dev/js/src/dropdown.js#L455 just after initial checks which are finishing the event handling, but in following lines there are further check which potentially could finish the handling. Propagation should be stopped after those checks.

Please see related PR with the fix.

Similar finding was created for v3: #15065 It was found as valid issue: #15065 (comment) however it was never fixed.

Thanks ans Regards,
Łukasz

[luktom]

PR to master can be find here: #30529, please see #30529 (comment) Backport of #28912 from v4 to v5 was needed.