Some of the snippets need to be updated later.

As of npm 5.0.0, installed modules are added as a dependency by default, so the --save option is no longer needed. The other save options still exist and are listed in the documentation for npm install.

`aria-haspopup` use requires the use of an ARIA `menu`, `listbox`, `tree`, `grid` or `dialog` (see https://www.w3.org/TR/wai-aria-1.1/#aria-haspopup)

in our use (as generic disclosure widgets), it's incorrect and sets up the wrong assumption/behavior from assistive technologies.

in future, we likely want to change our dropdowns to essentially be like a `dialog` - move focus to it when opened, possibly make it modal so focus is maintained inside it and the rest of the page
is hidden/inert.

but for now, removing the incorrect attribute is probably the quickest, most immediate fix.

* Prep for v4.3.0

* More updates for v4.3.0.

* rerun to build docs source map

* Remove extra comma.

* Use curly braces in snippet.

Instead pass the class to the example include.

Similar to #28153

It broke the example include.

This is more efficient than transitioning the `left` property.

Mostly be consistent with the attributes' order and improve compression when possible.

The previous was too light.