When a DOM node is passed to an HTML tooltip, the `title` node is only
moved if it is not already in the tooltip. Otherwise, `empty()` is used
instead of `detach()` before appending the `title` to avoid memory
leaks. If a DOM node is passed to a plain text tooltip, its text is
copied via jQuery `.text()`.

Replaces `.detach()` with `.empty()`, as `.detach()` is almost never
useful but instead leaks memory. The difference between `empty` and
`detach` is that the latter keeps all the attached jQuery events/data.
However, since we do not return the previous children, the user would
have to keep these themselves, thus they can `detach()` if necessary.

This is a port of https://github.com/twbs/bootstrap/pull/14552 to v4.

Use `https` when possible.

rm unused $state param from form-control-validation mixin

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Fix the JS errors due to jekyll-search.

Remove the now unused grunt-contrib-jade references.

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1) Update it to v1.0.8
2) Include jekyll-search where it's used only

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Update QUnit to v1.18.0.

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Remove defunct responsive-(in)visibility mixins

inline the one remaining usage into .hidden-print's definition
rm now-empty scss/_utilities-responsive.scss file

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Clear out non-v4 docs translations

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Bump year in jumbotron example

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Rebased & tweaked version of #17272

fixes #17097: Go back to using jQuery's text and html methods since innerText is nonstandard and not present in Firefox

Closes #17272 by merging a tweaked version of it.

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Add babel:dev to Sauce Grunt subtasks so we don't test stale JS

Refs #17328

Add babel:dev to dist-js so `grunt test` doesn't use stale JS

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Closes #17319 by merging it.

rm broken bundle update task & defunct custom RubyGem caching scheme

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[v4] Fix for Meteor package: removed font files