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Every built-in element is :defined - #193
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This one sits with #190 and #191 and #192, which touch the conformance fixes found by comparing against Chromium. They do not depend on each other. All seventeen in the series cherry-pick onto master in any order, and I checked that in both directions, so any one of these can land alone. The order below is the one they read best in: |
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':defined' asks the custom element registry about the candidate's tag name and requires an instanceof match, so it matches upgraded custom elements and nothing else. Every built-in element is defined; only a custom element can be undefined, and only until a definition exists and it has been upgraded. Browsers read it off the element's custom element state, where uncustomized and custom are the two that count as defined. https://github.com/chromium/chromium/blob/155.0.8041.1/third_party/blink/renderer/core/dom/element.h#L1201 The test reads the hyphen in the name first, which is what makes a name a custom element name, and asks for the 'is' attribute only when there is none, so an ordinary element costs one string scan. References: - Spec: https://dom.spec.whatwg.org/#concept-element-defined — uncustomized and custom are the two states that count as defined - Spec: https://html.spec.whatwg.org/#custom-elements-core-concepts — what makes a name a custom element name - Chromium: https://github.com/chromium/chromium/blob/155.0.8041.1/third_party/blink/renderer/core/dom/element.h#L1201 — the state read, with the same spec link in its own comment - Chromium: https://github.com/chromium/chromium/blob/155.0.8041.1/third_party/blink/renderer/core/css/selector_checker.cc#L3139 — ':defined' is that and nothing else - MDN: https://developer.mozilla.org/en-US/docs/Web/CSS/:defined
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Fix
Match built-in HTML, SVG, and MathML elements with :defined. Use native custom-element state when available, with a registry fallback for hosts that cannot provide it. Keep native-matcher reentry guarded.
Tests
Focused tests cover ordinary elements, autonomous custom elements, customized built-ins, upgrades, cached queries, and native state after is-attribute changes. A Chromium test compares results before and after install().
413 Node tests and all 43 WPT pages pass. Type checks, lint, and the Chromium comparison pass. Combined coverage passes every unchanged threshold.