Pasting a web archive drops <picture> when wrapped in a <span>

[pxlcoder]

efc8e7c

Pasting a web archive drops <picture> when wrapped in a <span>
https://bugs.webkit.org/show_bug.cgi?id=274062
rdar://127319160

Reviewed by Richard Robinson and Abrar Rahman Protyasha.

Pasting a web archive results in markup simplification being performed in
`SimplifyMarkupCommand`, via `ReplaceSelectionCommand`.

However, the logic for simplifying markup is incorrect. It currently
treats all inline elements that have the same style as equivalent. Then,
equivalent elements are removed bottom-up. This means that a `<picture>`
inside a `<span>` will be removed, as `<picture>` is an inline element,
with no custom style. Removing `<picture>` is incorrect, as it can affect the
rendered content due to source selection.

Fix by excluding `<picture>` from markup simplification. A better solution
would be to eliminate the `<span>` rather than the `<picture>`. However, that
approach requires a complete rewrite of the markup simplification algorithm.

* Source/WebCore/editing/SimplifyMarkupCommand.cpp:
(WebCore::SimplifyMarkupCommand::doApply):
* Tools/TestWebKitAPI/Tests/WebKitCocoa/PasteWebArchive.mm:
(TEST(PasteWebArchive, PreservesPictureInsideSpan)):

Canonical link: https://commits.webkit.org/278714@main

15c8ae6

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	⏳ 🛠 wpe-skia
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 15c8ae6)

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	⏳ 🛠 wpe-skia
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 278714@main (efc8e7c): https://commits.webkit.org/278714@main

Reviewed commits have been landed. Closing PR #28451 and removing active labels.