September 2020 - webkit-dev - lists.webkit.org

Request for position on Event Timing
by Rob Buis 23 Oct '20

23 Oct '20

Hi Webkit-Dev, I would like to get an official position from Webkit on the Event Timing Web Perf API. Besides providing information about input event latency it can be used to obtain First Input Timing metrics. This specification builds on the Performance Timeline specification, which is implemented in Webkit. Chrome has implemented the Event Timing API, see the chrome status entry below. - Specification: https://wicg.github.io/event-timing/ - Explainer: https://github.com/WICG/event-timing - MDN: https://developer.mozilla.org/en-US/docs/Web/API/PerformanceEventTiming - ChromeStatus: https://chromestatus.com/feature/5167290693713920 - Caniuse.com URL: https://caniuse.com/#feat=mdn-api_performanceeventtiming Regards, Rob.

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Request for position on isInputPending
by Andrew Comminos 29 Sep '20

29 Sep '20

Hey all, We're looking to gather a position from WebKit folks on isInputPending, an API to query for the presence of pending input events. It allows sites to reduce event latency by yielding during longer computational tasks, without sacrificing throughput otherwise. Explainer: https://github.com/WICG/is-input-pending/ Spec: https://wicg.github.io/is-input-pending/ Thanks a bunch! Andrew

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Request for position on Permissions-Policy header
by Ian Clelland 29 Sep '20

29 Sep '20

(Sending this from the right email address this time, hopefully) Hi WebKit! I'd like to ask WebKit leads for their stance on the Permissions-Policy header (https://www.chromestatus.com/feature/5745992911552512) Permissions Policy is the new (since https://github.com/w3c/webappsec-permissions-policy/issues/359) name for Feature Policy, and the Permissions-Policy header is part of that spec. WebKit has supported Feature Policy through the <iframe allow> attribute for some time, and the header has been designed to augment that functionality, by allowing sites to control which origins should never be granted use of powerful features. (Previously, the Feature-Policy header could be used to implicitly *grant* that delegation, rather than blocking it; that has been changed in response to developer feedback) I'm happy to discuss this in any forum, if folks have questions. Thanks! Ian Other references: Spec: https://w3c.github.io/webappsec-permissions-policy/ Tag review: https://github.com/w3ctag/design-reviews/issues/341 Original intent to prototype in Blink: https://groups.google.com/a/chromium.org/d/msg/blink-dev/As1ABvc2QdA/yZSpPX…

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Implementing MathML stylistic attributes in WebKit
by Frédéric Wang 28 Sep '20

28 Sep '20

Hello, Currently MathML attributes mathvariant, displaystyle and scriptlevel [1] [2] are implemented in WebKit using custom "style resolution" and "one-glyph rendering" inside the MathML layout code [3] [4] [5]. These features involve text rendering and interaction with CSS font-size, so it is difficult to implement them properly and completely that way. There are known bugs and missing features right now (e.g. mathvariant transform only applies to one-character strings, automatic displaystyle/scriptlevel does not work with fractions, etc) Several years ago, Gecko used to do something similar but that was causing a lot of problems (dynamic update, assertion failures...). At the end, this is now implemented in Gecko more reliably by mapping the attributes to internal CSS properties ; [6] is based on that. When I tried to do something like this in WebKit three years ago, I was only able to rely on proprietary -webkit-* extensions exposed to users [7]. So my questions are: (1) What is WebKit's mechanism to implement such stylistic attributes? (2) Is it possible to implement internal (i.e. not web-exposed to users) CSS properties/values in WebKit? (3) Is it ok to add more -webkit-* properties/values or should these properties be standardized at the CSS WG instead? I understand answers to these general questions from other browser project is either use internal properties or standardize them. Thanks, Frédéric PS: For a concrete example, see [8]. Automatic mathvariant is used for italic variables while font-size in fractions is calculated according to displaystyle / scriptlevel rules. The latter is incorrect (check the attached screenshot) while selection highlight is broken for the former. [1] https://mathml-refresh.github.io/mathml-core/#the-mathvariant-attribute [2] https://mathml-refresh.github.io/mathml-core/#the-displaystyle-and-scriptle… [3] https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/css/mathml.css [4] https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/rendering/mathm… [5] https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/rendering/mathm… [6] https://mathml-refresh.github.io/mathml-core/#css-extensions-for-math-layout [7] https://bugs.webkit.org/show_bug.cgi?id=133845#c5 [8] https://bug-201242-attachments.webkit.org/attachment.cgi?id=377730 -- Frédéric Wang

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Trailing space changes in "expected.txt" files
by Darin Adler 27 Sep '20

27 Sep '20

Hi folks. This afternoon, I changed dumpAsText so it strips trailing spaces. https://trac.webkit.org/changeset/267640 As part of that change, run-webkit-tests temporarily will ignore trailing spaces in expected.txt files, so they can be checked in with, or without, the spaces. Over the next few days, I’ll be checking in new versions of expected.txt files with the spaces at the ends of lines stripped. Once we have all the spaces stripped, then run-webkit-tests will go back to being strict about this again. This affects you if you have a patch that changes an expected.txt file; the space changes might lead to patch conflicts. If you do encounter conflicts, you can resolve them by rebasing and either regenerating the expected.txt files hand editing. Any newly-regenerated files won’t have any trailing spaces, and it’s best if newly checked in files do not have trailing spaces. If you run into any trouble with this, please get in touch. — Darin

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Problems with code review tool
by Ken Russell 26 Sep '20

26 Sep '20

Hi, Often when I publish code reviews on bugs.webkit.org, my browser tab gets stuck waiting for ews.webkit.org. Reloading the bug shows my comments, but because the submission doesn't complete, the review comments are still treated as pending by the tool, so publishing again causes duplicates. Has anyone else run into this? (My browser is Chrome on macOS.) Thanks, -Ken -- I support flexible work schedules, and I’m sending this email now because it is within the hours I’m working today. Please do not feel obliged to reply straight away - I understand that you will reply during the hours you work, which may not match mine. (credit: jparent@)

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Request for position: top-level await in JS
by Shu-yu Guo 25 Sep '20

25 Sep '20

Hi all, This is a request for the WebKit position on the top-level await JS proposal, which has been at Stage 3 in TC39 since June, 2019. Chrome is planning to ship it soon, likely in 88. (Interestingly, Node has flipped on the feature flag in V8 for top-level await by default, so it is already shipping for the Node ecosystem: https://github.com/nodejs/node/pull/34558) - Proposal: https://github.com/tc39/proposal-top-level-await - Specification: https://tc39.es/proposal-top-level-await/ - HTML integration PR: https://github.com/whatwg/html/pull/4352 - ChromeStatus: https://chromestatus.com/feature/5767881411264512 Cheers, Shu-yu Guo, V8

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Request for position: CSS Ruby Layout Module
by TAMURA, Kent 24 Sep '20

24 Sep '20

I'd like to request an official position of WebKit on CSS Ruby Layout Module [1], especially on the following features in the specification: - Ruby-specific 'display' property values: ruby, ruby-base, ruby-text, ruby-base-container, ruby-text-container - 'ruby-merge' property - 'ruby-align' property, and remove 'text-align' property support for <rt>. <rt> with text-align is used in 0.002% of page views. [2] - 'ruby-overhang' property Note that Firefox already shipped them. [1] https://drafts.csswg.org/css-ruby-1/ [2] https://www.chromestatus.com/metrics/feature/timeline/popularity/3313 -- TAMURA Kent Software Engineer, Google

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Question: referrerpolicy in Safari
by Maud Nalpas 23 Sep '20

23 Sep '20

Hi, I'm reaching out for a question about Referrer-Policy, more specifically about *element**-level* referrer policies (referrerpolicy=...) <https://www.w3.org/TR/referrer-policy/#referrer-policy-delivery-referrer-at…> . I would expect referrerpolicy on HTML elements to override a page's policy for the corresponding request. But this is not what I'm observing on Safari iOS (12) and Desktop (13, with "Prevent cross site tracking" on). And this diverges from Chrome's and Firefox's behaviour, which seem to honor referrerpolicy on elements. It's very possible that I'm mistaken and/or that my test site is wrong -- your input would help! Test Test site <https://site-one-dot-referrer-demo-280711.ey.r.appspot.com/stuff/detail?tag…> A policy can be selected in the blue button bar. To test referrerpolicy, the useful section is "Let's test element-based referrerpolicy" at the bottom of the page. Examples of unexpected behaviour (can be reproduced on the test site) 1. On https://site-one.example/path/foo with a document-level policy of strict-origin-when-cross-origin: - An <a> element with referrerpolicy=no-referrer-when-downgrade links to https://site-two.example (href). - Upon clicking the link and navigating to site-two, site-two gets the origin as a Referer in the request (Referer=https://site-one.example). - I would expect Referer=https://site-one.example/path/foo instead (and this is the behaviour in Chrome and Firefox). 2. On https://site-one.example/path/foo with a document-level policy of no-referrer: - An <img> element with referrerpolicy=strict-origin-when-cross-origin loads an image from *https://site-two.example <https://site-two.example>* (src). - site-two gets the full URL in this image request (Referer= https://site-one.example/path/foo) - I would expect Referer=https://site-one.example instead (and this is the behaviour in Chrome and Firefox). 3. On https://site-one.example/path/foo with an document-level policy of no-referrer-when-downgrade: A *referrerpolicy* on a <script> element seems to be honored on Safari desktop but not on iOS. Can this be? Why / What would be the expected behaviour? (I see that *referrerpolicy* support has been implemented <https://bugs.webkit.org/show_bug.cgi?id=179053>). Thank you! - Maud

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Request for position: 'display: list-item' by default for <summary>
by TAMURA, Kent 23 Sep '20

23 Sep '20

Hi, I'd like to request an official position of WebKit on changing the default ' display' property value of <summary> to 'list-item', and the relevant changes below: - Add 'disclosure-closed' and 'disclosure-open' keywords to ' list-style-type' property - Add ::marker pseudo element selector support to <summary> - Remove ::-webkit-details-marker pseudo element selector [1] is the usage counter for ::-webkit-details-marker, and it shows the ratio of pages with elements matched to ::-webkit-details-marker in author stylesheets. Currently the ratio is 0.0%. Firefox already shipped all of them. Specification: https://html.spec.whatwg.org/C/#the-details-and-summary-elements Specification: https://drafts.csswg.org/css-counter-styles-3/#disclosure-open [1] https://chromestatus.com/metrics/feature/timeline/popularity/3337 -- TAMURA Kent Software Engineer, Google

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