Add ::scroll-button feature (#2653)

* Add ::scroll-button feature.

* Generate scroll-buttons.yml.dist.

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Co-authored-by: Patrick Brosset <[email protected]>
Co-authored-by: Robert Flack <[email protected]>

Author: 3 people

features/scroll-buttons.yml

@@ -0,0 +1,4 @@
+name: ::scroll-button
+description: The `::scroll-button(<dir>)` CSS pseudo-element is a focusable button which scrolls its originating scroll container element in the specified direction.
+spec: https://drafts.csswg.org/css-overflow-5/#scroll-buttons
+group: scrolling

features/scroll-buttons.yml.dist

@@ -0,0 +1,6 @@
+# Generated from: scroll-buttons.yml
+# Do not edit this file by hand. Edit the source file instead!
+
+status:
+  baseline: false
+  support: {}