Bug 243787

Description:
imported/w3c/web-platform-tests/css/cssom/getComputedStyle-detached-subtree.html

The first failure I saw on the dashboard was on 7/21/2022 at 252721@main.  252720@main unified CSS property enablement and appears to be the cause.  This is only affecting iOS with model iPad (5th generation).

REPRODUCTION STEPS
I can reproduce this on 252720@main, but am unable to reproduce it on 252719@main or earlier.

Command: 
run-webkit-tests --ipad-simulator --model 'iPad (5th generation)' --exit-after-n-failures 1 --exit-after-n-crashes-or-timeouts 1 --iterations 50 --no-retry imported/w3c/web-platform-tests/css/cssom/getComputedStyle-detached-subtree.html

Result: 
Regressions: Unexpected text-only failures (1)
  imported/w3c/web-platform-tests/css/cssom/getComputedStyle-detached-subtree.html [ Failure ]

History:
https://results.webkit.org/?model=iPad%20(5th%20generation)&suite=layout-tests&test=imported%2Fw3c%2Fweb-platform-tests%2Fcss%2Fcssom%2FgetComputedStyle-detached-subtree.html&limit=50000

Diff:
--- /Volumes/Data/worker/Apple-iPadOS-15-Simulator-Release-WK2-Tests/build/layout-test-results/imported/w3c/web-platform-tests/css/cssom/getComputedStyle-detached-subtree-expected.txt
+++ /Volumes/Data/worker/Apple-iPadOS-15-Simulator-Release-WK2-Tests/build/layout-test-results/imported/w3c/web-platform-tests/css/cssom/getComputedStyle-detached-subtree-actual.txt
@@ -1,8 +1,8 @@
 
 PASS getComputedStyle returns no style for detached element
-FAIL getComputedStyle returns no style for element in non-rendered iframe (display: none) assert_equals: expected 0 but got 393
-FAIL getComputedStyle returns no style for element in non-rendered iframe (display: none) from iframe's window assert_equals: expected 0 but got 393
-FAIL getComputedStyle returns no style for element outside the flat tree assert_equals: expected 0 but got 393
-FAIL getComputedStyle returns no style for descendant outside the flat tree assert_equals: expected 0 but got 393
+FAIL getComputedStyle returns no style for element in non-rendered iframe (display: none) assert_equals: expected 0 but got 392
+FAIL getComputedStyle returns no style for element in non-rendered iframe (display: none) from iframe's window assert_equals: expected 0 but got 392
+FAIL getComputedStyle returns no style for element outside the flat tree assert_equals: expected 0 but got 392
+FAIL getComputedStyle returns no style for descendant outside the flat tree assert_equals: expected 0 but got 392
 PASS getComputedStyle returns no style for shadow tree outside of flattened tree