This adds a pseudo-class `:-moz-modal-dialog` to be able to track whether the
dialog is in the top layer in CSS.
This implements default styling for modal dialogs following the HTML standard.
Slightly off-extreme color scheme chosen for unstyled <dialog> elements.
- Block slot elements from being matched by ::slotted
- Ensure ::slotted() is serialized as a pseudo-element
- Add pref to control whether the pseudo-class is enabled
This modifies selector list parsing to accommodate being "forgiving". Aliases for the :is selector's former names were also included. Note that the older and prefixed variant `-moz-any` remains unforgiving.
* Stop calling SetHasDirAuto/ClearHasDirAuto in input element code
* Introduce event state flags that track the state of an element's dir attribute
* Rewrite our existing checks for the state of the dir attr on top of the new event state flags
* Add pseudo-classes for matching on the dir attribute states
* Use the new dir attribute pseudoclasses in html.css
Tag #1375
