Update normalize.css to the most recent version

Problem/Motivation

As part of #3094468: [plan] Update core JavaScript (and CSS) dependencies prior to 9.0.0-beta1 → we need to update Normalize.css to the most recent version - 8.0.1

Proposed resolution

Update normalize.css from 3.0.3 to 8.0.1.

Since Drupal core themes will not depend on Stable in future ( #3110855: Plan for removing dependency to Stable in Bartik/Seven/Claro/Umami → ), evaluate the changes (which are considerable) and determine which would cause unwanted regressions in core. If the regression is due to a bug/misjudgement in normalize.css, address in a normalize-fixes file. For other regressions, and provide customizations within the core theme experiencing the regression.

Once these regressions have been identified and addressed, add normalize.css version 3.0.3 as a BC layer to Stable. This means that themes depending on Stable (and by extension, Classy), will not be impacted by the update to normalize.css 8.0.1.

User interface changes

Drupal core themes are not impacted until #3094468: [plan] Update core JavaScript (and CSS) dependencies prior to 9.0.0-beta1 → . Minor regressions are expected in themes not extending Classy or Stable due to changes in normalize.css.

Remaining tasks

Original report

Firefox 49 is out and has support for <details> which means our polyfill doesn't kick in. Normalize.css sets <details> and <summary> element as display:block which means Firefox won't display the marker, they fixed this in 5.0.0 (https://github.com/necolas/normalize.css/issues/604).

Checkout comparison aligned by @droplet: (removed comments & unchanged rules, re-reordering to match v3)
https://www.drupal.org/files/issues/diff-manual-aligned-by-%40droplet.patch →

Here are the change logs for Normalize.css, starting at 4.0.0 (scroll up): https://github.com/necolas/normalize.css/blob/f06565fe8e0e1ad1b88f273271.... There are a lot of changes due to reorganization/sectioning of the code as well as comment changes.

There is one notable change that causes a regression in, at least, Seven: https://github.com/necolas/normalize.css/commit/02c5c7adbbec1707900fde86..., see the attached screenshot.

There may be regressions upgrading from 3.0.3 to the most recent normalize.css.

Upgrade core's Normalize to most recent version.
Normalize 3.0.3 should be copied to Stable. Stable needs to continue using 3.0.3 for BC.

Release note

The Drupal core normalize.css has been updated from 3.0.3 to 8.0.1. Themes that are not extending Stable or Classy should manually test in case they need to update. Stable theme will continue using normalize.css 3.0.3 for backwards compatibility. Read the change record on the normalize.css upgrade → for more information.