Intruduce concept of render tree rebuild root

[anttijk]

c7578c8

Intruduce concept of render tree rebuild root
https://bugs.webkit.org/show_bug.cgi?id=265284
rdar://118744369

Reviewed by Alan Baradlay.

Add mechanism to rebuild render subtree starting from an ancestor of the changed element.

We can simplify render tree mutations if some complex cases are handled by tearing
down a larger structure with all the associated anonymous boxes and rebuilding them.

Use the mechanism for <ruby> subtrees when style-based ruby is enabled. This gets tested by

fast/ruby/rubyDOM-insert-rt-block-1.html
fast/ruby/rubyDOM-insert-rt-block-2.html
fast/ruby/rubyDOM-insert-rt-block-3.html
fast/ruby/rubyDOM-remove-rt-block-1.html
fast/ruby/rubyDOM-remove-rt-block-2.html
fast/ruby/rubyDOM-remove-rt-block-3.html

* Source/WebCore/dom/Document.cpp:
(WebCore::Document::updateRenderTree):
* Source/WebCore/dom/Document.h:
* Source/WebCore/rendering/updating/RenderTreeBuilder.cpp:
(WebCore::RenderTreeBuilder::isRebuildRootForChildren):

Test if a given renderer is rebuild root for its children. For now this only tests for ruby.

* Source/WebCore/rendering/updating/RenderTreeBuilder.h:
* Source/WebCore/rendering/updating/RenderTreeUpdater.cpp:
(WebCore::findRenderingAncestor):
(WebCore::findRenderingRoot):
(WebCore::RenderTreeUpdater::commit):
(WebCore::RenderTreeUpdater::updateRebuildRoots):

In the beginning of a commit check if any of the rebuild roots need a wider rebuild.
Add all the new elements that will get rebuild to the style update.

* Source/WebCore/rendering/updating/RenderTreeUpdater.h:
* Source/WebCore/style/StyleUpdate.cpp:
(WebCore::Style::Update::addElement):
(WebCore::Style::Update::addPossibleRebuildRoot):

Keep track of the rebuild roots.

* Source/WebCore/style/StyleUpdate.h:
(WebCore::Style::Update::rebuildRoots const):

Canonical link: https://commits.webkit.org/271082@main

870d8a9

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 7252b82)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	🧪 ios-wk2	🧪 api-mac	🧪 api-wpe
	🧪 ios-wk2-wpt	🧪 mac-wk1	✅ 🛠 gtk
	✅ 🧪 api-ios	🧪 mac-wk2	🧪 gtk-wk2
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	🧪 api-gtk
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash e877284)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	🧪 ios-wk2	🧪 api-mac	🧪 api-wpe
	🧪 ios-wk2-wpt	🧪 mac-wk1	🛠 gtk
	🧪 api-ios	🧪 mac-wk2	🧪 gtk-wk2
	✅ 🛠 tv	🧪 mac-AS-debug-wk2	🧪 api-gtk
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 870d8a9)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 271082@main (c7578c8): https://commits.webkit.org/271082@main

Reviewed commits have been landed. Closing PR #20846 and removing active labels.