They are grunt-html-validation leftovers.

[ci skip]

Document JS test suite basics

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

Update initial release announcement dead link

Found it! They just changed the link.

[Fix #16001] Add link to Vietnamese translation

[Fix #16001] Add link to Vietnamese translation

Hiding an uninitialized tooltip/popover no longer initializes it

Erratum from #15496

Closes #15948 by merging it.

Closes #15946 by merging it.

Closes #15915 by merging it.

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

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

Properly document Modal#handleUpdate

Modal: Fix backdrop not readjusting when height changes

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

Add upstream patch comment for #15947

iOS fix for role="button" elements; [fixes #15935]

Disable deprecated QUnit global methods

Unit tests: Only display fixture on-screen for iOS

Handle multiple zero-offset Scrollspy elements.

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.

[Docs / README] Fix URL to match the plugin keyword recommendation

[Docs] Replace accidently removed tooltip / popover text

Fix URL to match the keyword

X-Ref #15742

cc: @mdo