as role="menu" is a very specific (and strict) ARIA pattern for
desktop-like application menus, and our dropdowns are often used
as pure navigation dropdowns, this change abandons ARIA menus for
a more open-ended and light-weight approach
(see http://heydonworks.com/practical_aria_examples/#submenus and
http://www.w3.org/WAI/tutorials/menus/flyout/#improve-screen-reader-support-using-wai-aria)
note that in dropdown.js, switched to now target ``.dropdown-menu``
instead of ``role["menu"]`` - this also prevents bootstrap scripts
from "bleeding" into non-bootstrap components on the same page.
also removed the ``role=["listbox"]`` part, which appears to be
vestigial/unused (only place in bootstrap that uses that
role are carousels, and their key handling is done separately)

when used with a sticky footer layout.
Adds visual test for affix with sticky footer.

Closes #15694.
Refs #15032.

Overall logic for this test appears broken, possibly relating to an
older version of Bootstrap that did not require explicit
`data-toggle="button"` on single toggle buttons?

Fixes issue #16008

Otherwise, the test doesn't properly fail when the fix is reverted.

Closes #16142 by merging it.

Closes #16219.

Closes #16151 by merging a rebased version of it that adds docs and 1 more assertion.

Closes #16073 by merging it

To ensure that we don't accidentally use any of the aliases.
This should prevent any future regressions from #12761.
Also updates the test suite since it now can't use these aliases either.

X-Ref: #15953
Closes #15952 by merging a tweaked version of it.
[skip sauce]
[skip validator]

Appears to be unnecessary and is broken by #16011,
which is otherwise quite sane.

Thanks to @peterblazejewicz & @Nikita240
Adds unit tests based on #14417
X-Ref: #14282
Closes #15807

[Fixes #15953] Implement `assert.expect` in each unit test

Fixes #15136.
Closes #15345.
Closes #15314.
Refs #14724, #14927.

When the first two elements in a scrollspy content block have a document
offset of zero (i.e. they're hard against the top of the page),
Scrollspy would switch between them on every scroll event.

This could happen, for example, in a system of nested sections:

```
<section id="animals">
  <section id="dogs">
	Content
  </section>
</section>
```

This ocurred because Scrollspy's check to see if it's at the end of the
array of sections uses `!arr[index]`. This misses the case where
`arr[index]` does exist and is zero.

This commit explicitly checks the array bounds.

Since only on iOS tests fail when the fixture is displayed off-screen, see https://travis-ci.org/twbs/bootstrap/jobs/52605742

Fixes #15741
Closes #15751 by merging it.

Refs http://qunitjs.com/upgrade-guide-2.x/#replace-qunit-jsdump-with-qunit-dump

Refs http://qunitjs.com/upgrade-guide-2.x/#replace-qunit-log-callback-with-qunit-log-callback-for-all-reporting-callbacks

Refs #15893

Fixes #15147.
Closes #15520 by merging it.