Problem: On https://turbovision.in6-addr.net a tiny-background-size +
background-repeat tile over a large painted area crashed WebContent.
Cause: BackgroundPainting was recording one paint command per tile for
any repeating background that’s not a decoded image. A small tile over a
large area could produce literally millions of commands — resulting in a
display list exceeding MAX_MESSAGE_PAYLOAD_SIZE, and tripping an assert.
Fix: When a repeating AbstractImageStyleValue would emit more tiles than
a fixed threshold, record a single tile into a nested display list and,
reusing some existing SVG pattern machinery, fill the coverage rect with
a PatternPaintStyle. We render the tile once, and repeat it with a
tiling shader — so the display list holds a single command regardless of
tile count. Normal backgrounds keep their exact per-tile painting.
Fixes https://github.com/LadybirdBrowser/ladybird/issues/9876
