Fixesreadest/readest#4785
Swipe page turns dropped frames, worst when crossing .xhtml section
boundaries. The paginator's #replaceBackground rebuilt its whole paint
context every animation frame (a getComputedStyle plus one
getBoundingClientRect per rendered view), and that per-frame cost scales
with the number of loaded views, which peaks at a boundary where adjacent
sections are preloaded.
Bumps the foliate-js submodule to 15fc999 (readest/foliate-js#41) to
snapshot the paint context once per gesture and reuse it on every frame,
and to defer the heavy mid-drag section preload off the active drag. The
bump also advances foliate-js to current main, picking up the
gpu-composite page-turn opt-in (readest/foliate-js#39).
Adds a real-browser test that drives an animated turn and a synthetic drag
and asserts the section <html> computed style is read a small constant
number of times instead of once per frame (snap 39 -> <=3, drag 7 -> <=1).
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Huang Xin
a0227f98e2