Fix ::backdrop/dialog/popover not appearing in top layer

[amoshydra]

⚠️ this is a poc, not tested yet. I am not familiar with this code base. feel free to take over and re-create this PR

Description

Fix ::backdrop/dialog/popover not appearing in top layer

Disable-CSS-blink-feature-support.patch made ConsumeBlinkFeatureFn always return false, which broke @supports blink-feature(OverlayProperty) in the UA stylesheet. Upstream Chromium M147 wrapped dialog:modal { overlay: auto } inside @supports blink-feature(OverlayProperty), so this rule was never applied in Cromite, preventing dialog/popover from entering the top layer.

Fix: only block blink-feature() for author (website) stylesheets. UA stylesheets (browser built-in CSS like html.css) still need it.

Fixes #2918
Fixes #2895

All submissions

• there are no other open Pull Requests for the same update/change
• Bromite can be built with these changes
• I have tested that the new change works as intended (AVD or physical device will do)

Format

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• patch description contains explanation of changes
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[larena1]

@uazo could you look into this ASAP? Many websites are unusable in Cromite currently, e.g. the search on Airbnb and others.

[uazo]

Thanks! Seriously, thank you for finding the bug!

Your code doesn't compile, but I'll take care of it now.
There's just one problem: when I wrote it, kUASheetMode was used for the Speculation Rules; I need to check if that's still the case