[iOS WK2] position:fixed inside oveflow:scroll is jumpy
https://bugs.webkit.org/show_bug.cgi?id=196238
Reviewed by Antti Koivisto.
Source/WebCore:
We were inadvertently making Positioned nodes for position:fixed, which is unnecessary because
Fixed nodes handle them, and harmful because they introduced unwanted layer movement.
Tests: scrollingcoordinator/ios/fixed-in-overflow-scroll-scrolling-tree.html
scrollingcoordinator/ios/fixed-in-overflow-scroll.html
* rendering/RenderLayerCompositor.cpp:
(WebCore::RenderLayerCompositor::computeCoordinatedPositioningForLayer const):
LayoutTests:
fixed-in-overflow-scroll-scrolling-tree.html actually tests the fix.
For some reason fixed-in-overflow-scroll.html doesn't show the jumpiness, but it's
a good test to have nonetheless.
Other minor cleanup.
* resources/ui-helper.js:
(window.UIHelper.immediateScrollElementAtContentPointToOffset):
* scrollingcoordinator/ios/fixed-in-overflow-scroll-expected.html: Added.
* scrollingcoordinator/ios/fixed-in-overflow-scroll-scrolling-tree-expected.txt: Added.
* scrollingcoordinator/ios/fixed-in-overflow-scroll-scrolling-tree.html: Copied from LayoutTests/scrollingcoordinator/ios/ui-scrolling-tree.html.
* scrollingcoordinator/ios/fixed-in-overflow-scroll.html: Added.
* scrollingcoordinator/ios/ui-scrolling-tree.html:
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@243513
268f45cc-cd09-0410-ab3c-
d52691b4dbfc