script: Clear style data from detached subtrees when attaching a shadow DOM by mrobinson · Pull Request #44259 · servo/servo

mrobinson · 2026-04-16T08:34:52Z

Instead of just clearing layout data, also clear style data from
descendants that are now no longer part of the flat tree when attaching
shadow DOM. This ensures that Stylo does not try to process them during
restyling. This matches what Gecko does.

Testing: This change adds a crash test and also causes a few subtests
to start passing.
Fixes: #40731.

servo-wpt-sync · 2026-04-16T08:39:01Z

🤖 Opened new upstream WPT pull request (web-platform-tests/wpt#59262) with upstreamable changes.

…ow DOM Instead of just clearing layout data, also clear style data from descendants that are now no longer part of the flat tree when attaching shadow DOM. This ensures that Stylo does not try to process them during restyling. This matches what Gecko does. Signed-off-by: Martin Robinson <mrobinson@fastmail.fm>

github-actions · 2026-04-16T09:02:06Z

🔨 Triggering try run (#24501613389) for Linux (WPT)

servo-wpt-sync · 2026-04-16T09:05:16Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#59262).

github-actions · 2026-04-16T09:38:23Z

Test results for linux-wpt from try job (#24501613389):

Flaky unexpected result (39)

CRASH [expected OK] /_mozilla/mozilla/input-value.html

ERROR [expected CRASH] /_webgl/conformance2/textures/misc/tex-3d-size-limit.html (#42881)

PASS [expected FAIL] subtest: WebGL test #1

FAIL [expected PASS] subtest: WebGL test #3

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : texImage3D should fail for dimension out of range. expected true got false

FAIL [expected PASS] subtest: WebGL test #4

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : texImage3D should fail for dimension out of range. expected true got false

FAIL [expected PASS] subtest: WebGL test #5

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : texImage3D should fail for dimension out of range. expected true got false

FAIL [expected PASS] subtest: WebGL test #6

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : texImage3D should fail for dimension out of range. expected true got false

FAIL [expected PASS] subtest: WebGL test #7

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : texImage3D should fail for dimension out of range. expected true got false

FAIL [expected PASS] subtest: WebGL test #8

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : texImage3D should fail for dimension out of range. expected true got false

FAIL [expected PASS] subtest: WebGL test #9

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : texImage3D should fail for dimension out of range. expected true got false

FAIL [expected PASS] subtest: WebGL test #10

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : texImage3D should fail for dimension out of range. expected true got false

FAIL [expected PASS] subtest: WebGL test #11

assert_true: getError expected: INVALID_VALUE. Was NO_ERROR : texImage3D should fail for dimension out of range. expected true got false

And 27 more unexpected results...

OK /beacon/beacon-basic.https.window.html (#41723)
- FAIL [expected PASS] subtest: Payload size restriction should be accumulated: type = arraybuffer
```
assert_false: expected false got true
```
CRASH [expected OK] /content-security-policy/meta/sandbox-iframe.html (#43478)
FAIL [expected PASS] /css/css-backgrounds/background-size-041.html
OK /css/css-cascade/layer-cssom-order-reverse.html (#36094)
- FAIL [expected PASS] subtest: Delete layer invalidates @font-face
```
assert_equals: expected "220px" but got "133px"
```
OK /css/css-cascade/layer-font-face-override.html (#35935)
- PASS [expected FAIL] subtest: @font-face override update with appended sheet 1
- PASS [expected FAIL] subtest: @font-face override update with appended sheet 2
FAIL [expected PASS] /css/css-ui/appearance-button-001.html
FAIL [expected PASS] /css/css-ui/appearance-listbox-001.html
PASS [expected FAIL] /css/css-ui/appearance-menulist-button-002.tentative.html
FAIL [expected PASS] /css/css-ui/compute-kind-widget-generated/grouped-kind-of-widget-fallback-border-top-left-radius-001.html
CRASH [expected OK] /fetch/api/cors/cors-redirect.any.worker.html
TIMEOUT [expected OK] /fetch/api/redirect/redirect-keepalive.https.any.html (#32153)
- TIMEOUT [expected PASS] subtest: [keepalive][iframe][load] mixed content redirect; setting up
```
Test timed out
```
OK [expected ERROR] /fetch/fetch-later/quota/same-origin-iframe/sandboxed-iframe.https.window.html (#41704)
OK /fetch/metadata/generated/css-font-face.https.sub.tentative.html (#32732)
- PASS [expected FAIL] subtest: sec-fetch-dest
- PASS [expected FAIL] subtest: sec-fetch-storage-access - Cross-site
OK /fetch/metadata/window-open.https.sub.html (#40339)
- FAIL [expected PASS] subtest: Same-site window, forced, reloaded
```
The operation is insecure.
```
ERROR [expected OK] /focus/focus-event-after-switching-iframes.sub.html (#40368)
CRASH [expected OK] /html/browsers/browsing-the-web/history-traversal/api-availability.html
OK /html/browsers/browsing-the-web/navigating-across-documents/replace-before-load/a-click.html (#28697)
- PASS [expected FAIL] subtest: aElement.click() before the load event must NOT replace

OK [expected TIMEOUT] /html/browsers/browsing-the-web/navigating-across-documents/replace-before-load/form-submit-button-click.html (#44099)

FAIL [expected TIMEOUT] subtest: Replace before load, triggered by submitButton.click()

assert_equals: expected "http://web-platform.test:8000/common/blank.html?thereplacement=" but got "http://web-platform.test:8000/html/browsers/browsing-the-web/navigating-across-documents/replace-before-load/resources/code-injector.html?pipe=sub(none)&amp;code=%0A%20%20%20%20const%20form%20%3D%20document.createElement(%22form%22)%3B%0A%20%20%20%20form.action%20%3D%20%22%2Fcommon%2Fblank.html%22%3B%0A%0A%20%20%20%20const%20input%20%3D%20document.createElement(%22input%22)%3B%0A%20%20%20%20input.type%20%3D%20%22hidden%22%3B%0A%20%20%20%20input.name%20%3D%20%22thereplacement%22%3B%0A%20%20%20%20form.append(input)%3B%0A%0A%20%20%20%20const%20button%20%3D%20document.createElement(%22button%22)%3B%0A%20%20%20%20button.type%20%3D%20%22submit%22%3B%0A%20%20%20%20form.append(button)%3B%0A%0A%20%20%20%20document.currentScript.before(form)%3B%0A%20%20%20%20button.click()%3B%0A%20%20"

OK [expected TIMEOUT] /html/browsers/browsing-the-web/navigating-across-documents/replace-before-load/form-submit.html (#44028)
OK /html/browsers/history/the-history-interface/traverse_the_history_2.html (#21383)
- PASS [expected FAIL] subtest: Multiple history traversals, last would be aborted
OK [expected TIMEOUT] /html/semantics/embedded-content/media-elements/src_object_blob.html (#40340)
- PASS [expected TIMEOUT] subtest: HTMLMediaElement.srcObject blob
TIMEOUT [expected OK] /html/semantics/embedded-content/the-iframe-element/iframe_sandbox_navigate_other_frame_popup.sub.html (#39702)
- TIMEOUT [expected FAIL] subtest: Sandboxed iframe can not navigate other frame's popup
```
Test timed out
```
OK /html/semantics/forms/form-submission-0/jsurl-form-submit.tentative.html (#36489)
- PASS [expected FAIL] subtest: Verifies that form submissions scheduled inside javascript: urls take precedence over the javascript: url's return value.
OK /html/semantics/scripting-1/the-script-element/module/choice-of-error-1.html (#44058)
- PASS [expected FAIL] subtest: Parse errors in different files should be reported depending on different roots
OK /html/semantics/scripting-1/the-script-element/module/dynamic-import/blob-url.any.html (#33948)
- FAIL [expected PASS] subtest: Revoking a blob URL immediately after calling import will not fail
```
promise_test: Unhandled rejection with value: object "TypeError: Module fetching failed"
```
ERROR [expected TIMEOUT] /performance-timeline/not-restored-reasons/abort-block-bfcache.window.html (#42802)
OK [expected CRASH] /resource-timing/render-blocking-status-link.html (#41664)
OK /resource-timing/test_resource_timing.https.html (#25216)
- PASS [expected FAIL] subtest: PerformanceEntry has correct name, initiatorType, startTime, and duration (xmlhttprequest)
OK [expected TIMEOUT] /trusted-types/trusted-types-navigation.html?06-10 (#37920)
- PASS [expected TIMEOUT] subtest: Navigate a frame via anchor with javascript:-urls w/ default policy in report-only mode.
- FAIL [expected NOTRUN] subtest: Navigate a window via anchor with javascript:-urls w/ a default policy throwing an exception in enforcing mode.
```
promise_test: Unhandled rejection with value: "Unexpected message received: \"No securitypolicyviolation reported!\""
```
- FAIL [expected NOTRUN] subtest: Navigate a window via anchor with javascript:-urls w/ a default policy throwing an exception in report-only mode.
```
promise_test: Unhandled rejection with value: "Unexpected message received: \"No securitypolicyviolation reported!\""
```
TIMEOUT /trusted-types/trusted-types-navigation.html?31-35 (#38034)
- TIMEOUT [expected PASS] subtest: Navigate a frame via form-submission with javascript:-urls in report-only mode.
```
Test timed out
```
- NOTRUN [expected TIMEOUT] subtest: Navigate a frame via form-submission with javascript:-urls w/ default policy in report-only mode.
OK /trusted-types/trusted-types-reporting.html (#43737)
- PASS [expected FAIL] subtest: Trusted Type violation report: creating a forbidden-but-not-reported policy.
- PASS [expected FAIL] subtest: Trusted Type violation report: sample for SVGScriptElement href assignment by setAttribute
OK /visual-viewport/resize-event-order.html (#41981)
- PASS [expected FAIL] subtest: Popup: DOMWindow resize fired before VisualViewport.

OK /webaudio/the-audio-api/the-audiobuffersourcenode-interface/sub-sample-buffer-stitching.html (#22849)

FAIL [expected PASS] subtest: buffer-stitching-2

assert_approx_equals: Stitched sine‑wave buffers at sample rate 43800 sample[1239] |-2.5853680307719173e-10 - 0.7628296613693237| = 0.7628296616278605 &gt; 0.0038986 expected 0.7628296613693237 +/- 0.0038986 but got -2.5853680307719173e-10

OK /webdriver/tests/classic/element_click/navigate.py
- FAIL [expected PASS] subtest: test_numbers_link
```
webdriver.error.NoSuchWindowException: no such window (404): No such window
```
OK /webdriver/tests/classic/element_send_keys/form_controls.py
- FAIL [expected PASS] subtest: test_input
```
webdriver.error.NoSuchWindowException: no such window (404): No such window
```
OK /webdriver/tests/classic/find_elements_from_element/find.py
- FAIL [expected PASS] subtest: test_null_parameter_value
```
webdriver.error.NoSuchWindowException: no such window (404): No such window
```
TIMEOUT [expected OK] /webstorage/localstorage-about-blank-3P-iframe-opens-3P-window.partitioned.html (#29053)
- TIMEOUT [expected FAIL] subtest: StorageKey: test 3P about:blank window opened from a 3P iframe
```
Test timed out
```

Stable unexpected results that are known to be intermittent (19)

TIMEOUT /FileAPI/url/url-in-tags-revoke.window.html (#19978)
- TIMEOUT [expected PASS] subtest: Fetching a blob URL immediately before revoking it works in <script> tags.
```
Test timed out
```
TIMEOUT [expected OK] /_mozilla/mozilla/window-resize-event.html (#36741)
- TIMEOUT [expected PASS] subtest: Popup onresize event fires after resizeTo
```
Test timed out
```
OK [expected ERROR] /_webgl/conformance2/textures/misc/origin-clean-conformance-offscreencanvas.html (#29589)
- PASS [expected NOTRUN] subtest: Overall test
TIMEOUT [expected OK] /credential-management/credentialscontainer-frame-basics.https.html (#39430)
- TIMEOUT [expected FAIL] subtest: navigator.credentials should be undefined in documents generated from data: URLs.
```
Test timed out
```
OK /css/css-fonts/generic-family-keywords-001.html (#37467)
- PASS [expected FAIL] subtest: @font-face matching for quoted and unquoted generic(kai)
OK /css/css-fonts/generic-family-keywords-003.html (#38994)
- PASS [expected FAIL] subtest: @font-face matching for quoted and unquoted cursive (drawing text in a canvas)
- PASS [expected FAIL] subtest: @font-face matching for quoted and unquoted monospace (drawing text in a canvas)
- PASS [expected FAIL] subtest: @font-face matching for quoted and unquoted math (drawing text in a canvas)
- PASS [expected FAIL] subtest: @font-face matching for quoted and unquoted generic(kai) (drawing text in a canvas)
- PASS [expected FAIL] subtest: @font-face matching for quoted and unquoted generic(nastaliq) (drawing text in a canvas)
- FAIL [expected PASS] subtest: @font-face matching for quoted and unquoted ui-sans-serif (drawing text in a canvas)
```
assert_equals: unquoted ui-sans-serif does not match @font-face rule expected 40 but got 125
```
OK [expected ERROR] /fetch/fetch-later/quota/same-origin-iframe/accumulated-oversized-payload.https.window.html (#41705)
TIMEOUT /fetch/metadata/generated/css-images.https.sub.tentative.html (#42229)
- FAIL [expected PASS] subtest: content sec-fetch-site - Same-Origin -> Same Origin
```
assert_unreached: Reached unreachable code
```
TIMEOUT [expected ERROR] /html/browsers/browsing-the-web/history-traversal/pageswap/pageswap-initial-navigation.html (#40387)
OK /html/browsers/browsing-the-web/navigating-across-documents/navigation-unload-same-origin-fragment.html (#20768)
- FAIL [expected PASS] subtest: Tests that a fragment navigation in the unload handler will not block the initial navigation
```
assert_equals: expected "" but got "#fragment"
```
OK /html/browsers/history/the-history-interface/traverse_the_history_4.html (#21383)
- FAIL [expected PASS] subtest: Multiple history traversals, last would be aborted
```
assert_array_equals: Pages opened during history navigation expected property 1 to be 5 but got 3 (expected array [6, 5] got [6, 3])
```
OK /html/browsers/history/the-history-interface/traverse_the_history_5.html (#21383)
- FAIL [expected PASS] subtest: Multiple history traversals, last would be aborted
```
assert_array_equals: Pages opened during history navigation expected property 1 to be 5 but got 3 (expected array [6, 5] got [6, 3])
```
TIMEOUT /html/interaction/focus/the-autofocus-attribute/supported-elements.html (#24145)
- FAIL [expected NOTRUN] subtest: Host element with delegatesFocus should support autofocus
```
assert_equals: expected Element node &lt;div autofocus=""&gt;&lt;/div&gt; but got Element node &lt;body&gt;&lt;div autofocus=""&gt;&lt;/div&gt;&lt;/body&gt;
```
- TIMEOUT [expected NOTRUN] subtest: Host element with delegatesFocus including no focusable descendants should be skipped
```
Test timed out
```
ERROR [expected OK] /intersection-observer/v2/animated-opacity.html (#40827)
OK /mixed-content/tentative/autoupgrades/mixed-content-cors.https.sub.html (#41123)
- PASS [expected FAIL] subtest: Cross-Origin video should get upgraded even if CORS is set
OK /resource-timing/test_resource_timing.html (#25720)
- PASS [expected FAIL] subtest: PerformanceEntry has correct name, initiatorType, startTime, and duration (img)
OK /touch-events/single-tap-when-touchend-listener-use-sync-xhr.html (#41175)
- PASS [expected FAIL] subtest: Click event should be fired when touchend opens synchronous XHR
OK [expected TIMEOUT] /trusted-types/trusted-types-navigation.html?01-05 (#38975)
- PASS [expected TIMEOUT] subtest: Navigate a window via anchor with javascript:-urls in report-only mode.
- PASS [expected NOTRUN] subtest: Navigate a window via anchor with javascript:-urls w/ default policy in report-only mode.
- PASS [expected NOTRUN] subtest: Navigate a frame via anchor with javascript:-urls in enforcing mode.
TIMEOUT [expected OK] /trusted-types/trusted-types-navigation.html?26-30 (#38807)
- TIMEOUT [expected PASS] subtest: Navigate a window via form-submission with javascript:-urls in report-only mode.
```
Test timed out
```
- NOTRUN [expected PASS] subtest: Navigate a window via form-submission with javascript:-urls w/ default policy in report-only mode.
- NOTRUN [expected PASS] subtest: Navigate a frame via form-submission with javascript:-urls in enforcing mode.
- NOTRUN [expected PASS] subtest: Navigate a frame via form-submission with javascript:-urls w/ default policy in enforcing mode.

github-actions · 2026-04-16T09:38:32Z

✨ Try run (#24501613389) succeeded.

mrobinson requested a review from gterzian as a code owner April 16, 2026 08:34

servo-highfive added the S-awaiting-review There is new code that needs to be reviewed. label Apr 16, 2026

servo-wpt-sync mentioned this pull request Apr 16, 2026

script: Clear style data from detached subtrees when attaching a shadow DOM web-platform-tests/wpt#59262

Merged

mrobinson force-pushed the clear-style-data branch from 6625546 to 8abeb1e Compare April 16, 2026 09:01

mrobinson added the T-linux-wpt Do a try run of the WPT label Apr 16, 2026

github-actions Bot removed the T-linux-wpt Do a try run of the WPT label Apr 16, 2026

TimvdLippe approved these changes Apr 16, 2026

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servo-highfive removed the S-awaiting-review There is new code that needs to be reviewed. label Apr 16, 2026

TimvdLippe added this pull request to the merge queue Apr 16, 2026

servo-highfive added the S-awaiting-merge The PR is in the process of compiling and running tests on the automated CI. label Apr 16, 2026

Merged via the queue into servo:main with commit b3fdbf9 Apr 16, 2026
68 checks passed

servo-highfive removed the S-awaiting-merge The PR is in the process of compiling and running tests on the automated CI. label Apr 16, 2026

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script: Clear style data from detached subtrees when attaching a shadow DOM#44259

script: Clear style data from detached subtrees when attaching a shadow DOM#44259
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