39c2c06

VTT cue positioning algorithm should use floats instead of ints
https://bugs.webkit.org/show_bug.cgi?id=319433
rdar://182250995

Reviewed by NOBODY (OOPS!).

Currently, WebKit fails WebVTT WPT 2_cues_overlapping_partially_move_up.html
and 2_cues_overlapping_partially_move_down.html. These tests check that when
a VTT file uses the line setting to position cues such that they overlap,
the browser moves the second cue as minimally as possible so that they do not overlap.

The rendered cues' top and bottom edges should be flush with each other, since the spec
expects the cue to be moved minimally and makes no indication that we should be
rounding to the nearest integer. However, WebKit's rendering of these vtt files
puts a gap between the two cues. This is caused by our use of integers in RenderVTTCue.
We should instead use floats.

No new test expectations due to bugs in the wpt tests that cause us to still fail them.
One a future patch fixes the tests the expectations will be updated.

* Source/WebCore/rendering/RenderVTTCue.cpp:
(WebCore::RenderVTTCue::unroundedAbsoluteBoundingBoxRect):
(WebCore::RenderVTTCue::isOutside const):
(WebCore::RenderVTTCue::rectIsWithinContainer const):
(WebCore::RenderVTTCue::overlappingObject const):
(WebCore::RenderVTTCue::overlappingObjectForRect const):
(WebCore::RenderVTTCue::moveIfNecessaryToKeepWithinContainer):
(WebCore::RenderVTTCue::findNonOverlappingPosition const):
(WebCore::RenderVTTCue::repositionCueSnapToLinesNotSet):
* Source/WebCore/rendering/RenderVTTCue.h:

39c2c06

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	⏳ 🧪 win-tests	🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		🛠 vision-apple
	✅ 🧪 ios-wk2-wpt	⏳ 🧪 api-mac-debug	✅ 🛠 gtk3-libwebrtc
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	⏳ 🛠 ios-safer-cpp	⏳ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision		✅ 🧪 api-gtk
	✅ 🛠 vision-sim	⏳ 🧪 mac-intel-wk2	⏳ 🛠 playstation
	✅ 🧪 vision-wk2	⏳ 🛠 mac-safer-cpp
	✅ 🛠 tv	✅ 🧪 mac-site-isolation
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim