Generate anonymous table cells for non-table-internal children of tables

[nicoburns]

Summary

Fixes the gov.uk homepage search box being unclickable.

Root cause: gov.uk's search component wraps the <input> in plain block <div>s that are direct children of a display: table element. In collect_table_cells, children with DisplayInside::Flow/FlowRoot/Flex/Grid were silently ignored ("probably a table caption"), so they were never added as layout children of the table grid. The input's wrapper (and the input) therefore got no layout at all — final_layout() stayed 0x0 — and Node::hit_inner rejects zero-sized nodes, making the search box impossible to click.

Fix: per CSS 2.2 §17.2.1, non-table-internal children of a table generate an anonymous table cell around them. collect_table_cells now treats such children like table cells (as their own anonymous single-span cell in the current row, bumping *row from 0 to 1 when they occur before any row), while skipping cell-only handling (colspan/rowspan attributes, border-collapse border zeroing, margin zeroing, first-cell-border capture) for non-cell children.

Verified against https://www.gov.uk: the search input now lays out at its rendered size and hit-testing at its center returns the input node; the rendered screenshot is unchanged/correct.

Regression tests added in tests/blitz-tests/tests/table_anonymous_cell.rs (layout + hit-test, and click-to-focus for an input inside a table's block child).

Link to Devin session: https://dioxus.staging.devinenterprise.com/sessions/e0b69caedcd34e829ff73fb7ff216a75
Open in Devin Desktop: https://dioxus.staging.devinenterprise.com/desktop/session/e0b69caedcd34e829ff73fb7ff216a75?variant=devin-insiders
Requested by: @nicoburns

WPT results

71 newly passing, 19 newly failing (net +52).

Full diff (90 changed tests)

+ Fail => Pass css/CSS2/backgrounds/background-applies-to-015.xht
+ Fail => Pass css/CSS2/backgrounds/background-attachment-applies-to-015.xht
+ Fail => Pass css/CSS2/backgrounds/background-color-applies-to-015.xht
+ Fail => Pass css/CSS2/backgrounds/background-image-applies-to-015.xht
+ Fail => Pass css/CSS2/backgrounds/background-repeat-applies-to-015.xht
- Pass => Fail css/CSS2/bidi-text/bidi-008a.xht
- Pass => Fail css/CSS2/bidi-text/bidi-008b.xht
+ Fail => Pass css/CSS2/borders/border-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-bottom-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-bottom-color-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-bottom-width-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-color-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-left-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-left-color-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-left-width-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-right-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-right-color-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-right-width-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-top-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-top-color-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-top-width-applies-to-015.xht
+ Fail => Pass css/CSS2/borders/border-width-applies-to-015.xht
+ Fail => Pass css/CSS2/colors/color-applies-to-015.xht
- Pass => Fail css/CSS2/css21-errata/s-11-1-1b-001.html
- Pass => Fail css/CSS2/css21-errata/s-11-1-1b-008.html
- Pass => Fail css/CSS2/css21-errata/s-11-1-1b-009.html
+ Fail => Pass css/CSS2/fonts/font-applies-to-015.xht
+ Fail => Pass css/CSS2/fonts/font-variant-applies-to-015.xht
+ Fail => Pass css/CSS2/fonts/font-weight-applies-to-015.xht
+ Fail => Pass css/CSS2/linebox/vertical-align-applies-to-015.xht
+ Fail => Pass css/CSS2/lists/list-style-applies-to-015.xht
+ Fail => Pass css/CSS2/lists/list-style-image-applies-to-015.xht
+ Fail => Pass css/CSS2/lists/list-style-type-applies-to-015.xht
+ Fail => Pass css/CSS2/margin-padding-clear/margin-applies-to-015.xht
+ Fail => Pass css/CSS2/margin-padding-clear/margin-left-applies-to-015.xht
+ Fail => Pass css/CSS2/margin-padding-clear/margin-right-applies-to-015.xht
+ Fail => Pass css/CSS2/margin-padding-clear/margin-top-applies-to-015.xht
+ Fail => Pass css/CSS2/margin-padding-clear/padding-applies-to-015.xht
+ Fail => Pass css/CSS2/margin-padding-clear/padding-bottom-applies-to-015.xht
+ Fail => Pass css/CSS2/margin-padding-clear/padding-left-applies-to-015.xht
+ Fail => Pass css/CSS2/margin-padding-clear/padding-right-applies-to-015.xht
+ Fail => Pass css/CSS2/margin-padding-clear/padding-top-applies-to-015.xht
+ Fail => Pass css/CSS2/normal-flow/height-applies-to-015.xht
- Pass => Fail css/CSS2/normal-flow/inline-table-002a.xht
- Pass => Fail css/CSS2/normal-flow/inline-table-width-002b.xht
+ Fail => Pass css/CSS2/normal-flow/inline-table-zorder-002.xht
+ Fail => Pass css/CSS2/normal-flow/max-height-applies-to-015.xht
+ Fail => Pass css/CSS2/normal-flow/max-width-applies-to-015.xht
+ Fail => Pass css/CSS2/normal-flow/min-height-applies-to-015.xht
+ Fail => Pass css/CSS2/normal-flow/min-width-applies-to-015.xht
+ Fail => Pass css/CSS2/normal-flow/width-applies-to-015.xht
+ Fail => Pass css/CSS2/tables/anonymous-table-box-width-001.xht
+ Fail => Pass css/CSS2/text/letter-spacing-applies-to-015.xht
+ Fail => Pass css/CSS2/text/text-decoration-applies-to-015.xht
+ Fail => Pass css/CSS2/text/text-indent-applies-to-015.xht
+ Fail => Pass css/CSS2/text/white-space-applies-to-015.xht
+ Fail => Pass css/CSS2/text/word-spacing-applies-to-015.xht
- Pass => Fail css/CSS2/ui/outline-applies-to-016.xht
- Pass => Fail css/CSS2/ui/outline-applies-to-017.xht
- Pass => Fail css/css-break/table/break-before-second-row.html
- Pass => Fail css/css-break/table/caption-margin-002.html
- Pass => Fail css/css-break/table/caption-margin-005.html
+ Fail => Pass css/css-break/table/inside-flex-001.html
+ Fail => Pass css/css-break/table/monolithic-overflow-002.tentative.html
+ Fail => Pass css/css-break/table/monolithic-overflow-004.tentative.html
+ Fail => Pass css/css-break/table/repeated-section/image.tentative.html
+ Fail => Pass css/css-contain/contain-inline-size-table.html
- Pass => Fail css/css-contain/contain-size-056.html
- Pass => Fail css/css-contain/contain-size-table-caption-001.html
- Pass => Fail css/css-contain/content-visibility/content-visibility-094.html
- Pass => Fail css/css-contain/content-visibility/content-visibility-095.html
+ Fail => Pass css/css-flexbox/flexbox_flex-formatting-interop.html
+ Fail => Pass css/css-flexbox/flexbox_stf-table-singleline-2.html
+ Fail => Pass css/css-flexbox/flexbox_stf-table-singleline.html
- Pass => Fail css/css-flexbox/table-as-item-flex-cross-size.html
+ Fail => Pass css/css-flexbox/table-as-item-narrow-content.html
- Pass => Fail css/css-flexbox/table-as-item-stretch-cross-size-2.html
- Pass => Fail css/css-flexbox/table-as-item-stretch-cross-size.html
+ Fail => Pass css/css-flexbox/table-with-float-paint.html
+ Fail => Pass css/css-grid/grid-items/explicitly-sized-grid-item-as-table.html
+ Fail => Pass css/css-page/monolithic-overflow-009-print.html
+ Fail => Pass css/css-page/monolithic-overflow-010-print.html
+ Fail => Pass css/css-page/monolithic-overflow-011-print.html
+ Fail => Pass css/css-page/monolithic-overflow-017-print.html
+ Fail => Pass css/css-sizing/calc-margins-table-caption.html
+ Fail => Pass css/css-sizing/table-child-percentage-height-with-border-box.html
+ Fail => Pass css/css-sizing/table-percentage-max-width-beside-float.html
+ Fail => Pass css/css-tables/html-display-table.html
+ Fail => Pass css/css-tables/percent-height-overflow-auto-in-restricted-block-size-cell.html
+ Fail => Pass css/css-tables/percent-height-overflow-auto-in-unrestricted-block-size-cell.tentative.html

_{Generated by the WPT workflow.}

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