[iPhone] 39miles.com link is rendered at single-column layout in private browsing mode

[whsieh]

88351af

[iPhone] 39miles.com link is rendered at single-column layout in private browsing mode
https://bugs.webkit.org/show_bug.cgi?id=259129
rdar://112105451

Reviewed by Aditya Keerthi.

Add a missing 390pt screen dimension breakpoint when advanced privacy protections are enabled;
currently, this causes some websites that rely on the screen width for layout to assume that the
width of the page is larger than it actually is.

* Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm:
(WebKit::WebPage::screenSizeForFingerprintingProtections const):
* Tools/TestWebKitAPI/Tests/WebKit/AdvancedPrivacyProtections.mm:

Also, augment an existing API test to verify that the new screen size breakpoint behaves as
expected.

Canonical link: https://commits.webkit.org/265979@main

608d5da

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	✅ 🛠 gtk
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 api-gtk
	🛠 tv	✅ 🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 608d5da)

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	✅ 🛠 gtk
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 api-gtk
	🛠 tv	✅ 🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[whsieh]

Thanks for the review!

[webkit-commit-queue]

Committed 265979@main (88351af): https://commits.webkit.org/265979@main

Reviewed commits have been landed. Closing PR #15763 and removing active labels.