[Remote Inspection] Element targeting should additionally find nearby out-of-flow elements

[whsieh]

6458185

[Remote Inspection] Element targeting should additionally find nearby out-of-flow elements
https://bugs.webkit.org/show_bug.cgi?id=271616

Reviewed by Abrar Protyasha.

When targeting elements for remote inspection, additionally surface nearby elements which aren't
precisely under the hit test location. Our strategy for this consists of the following:

1.  While collecting targets, aggregate a `Region` containing the rects of all targeted out-of-flow
    elements (and hit-tested elements underneath targeted elements).

2.  After building the list of targets, scan the entire DOM for out-of-flow renderers that are also
    contained in the "nearby targets" region, which also satisfy the same criteria for element
    targeting.

3.  Add these as "nearby targets" to the final list of target infos, to the end of the array.

See below for more details.

Test: ElementTargeting.NearbyOutOfFlowElements

* Source/WebCore/page/ElementTargeting.cpp:
(WebCore::targetedElementInfo):

Refactor this code to pull common logic into lambdas, and implement the steps detailed above.

(WebCore::findTargetedElements):
* Source/WebCore/page/ElementTargetingTypes.h:
* Source/WebKit/Shared/WebCoreArgumentCoders.serialization.in:
* Source/WebKit/UIProcess/API/APITargetedElementInfo.h:
* Source/WebKit/UIProcess/API/Cocoa/WKWebView.mm:
(-[WKWebView _requestTargetedElementInfo:completionHandler:]):
* Source/WebKit/UIProcess/API/Cocoa/_WKTargetedElementInfo.h:

Add a new `isUnderPoint` property, which is `YES` for elements that are directly hit-tested, and
`NO` for nearby targets.

* Source/WebKit/UIProcess/API/Cocoa/_WKTargetedElementInfo.mm:
(-[_WKTargetedElementInfo isUnderPoint]):
* Source/WebKit/UIProcess/API/Cocoa/_WKTargetedElementRequest.h:

Add a new `canIncludeNearbyElements` (default: `YES`) which determines whether or not element
targeting should include elements that have not been hit-tested, but are visually contained within
another element that has been hit-tested.

* Source/WebKit/UIProcess/API/Cocoa/_WKTargetedElementRequest.mm:
(-[_WKTargetedElementRequest init]):
* Tools/TestWebKitAPI/TestWebKitAPI.xcodeproj/project.pbxproj:
* Tools/TestWebKitAPI/Tests/WebKitCocoa/ElementTargetingTests.mm:
(TestWebKitAPI::TEST):
* Tools/TestWebKitAPI/Tests/WebKitCocoa/element-targeting-2.html: Added.

Add a new API test to exercise the change.

Canonical link: https://commits.webkit.org/276670@main

e305a09

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Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
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✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
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	⏳ 🧪 ios-wk2-wpt	🧪 mac-wk1	🛠 wpe-skia
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[webkit-early-warning-system]

EWS run on current version of this PR (hash ab0b5e5)

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
🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv-sim		✅ 🧪 api-gtk
	🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 276670@main (6458185): https://commits.webkit.org/276670@main

Reviewed commits have been landed. Closing PR #26435 and removing active labels.