Auto merge of #21856 - zcorpan:zcorpan/remove-td-th-interfaces, r=jdm

Remove the HTMLTable{Header,Data}CellElement interfaces

Fixes #17222.

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This removes the `HTMLTableHeaderCellElement` and `HTMLTableDataCellElement` interfaces and uses the `HTMLTableCellElement` interface for both `th` and `td` elements, as per the spec.

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- [X] These changes fix #17222.

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components/script/dom/node.rs

@@ -2930,7 +2930,7 @@ impl Into<LayoutElementType> for ElementTypeId {
             ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLParagraphElement) => {
                 LayoutElementType::HTMLParagraphElement
             },
-            ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLTableCellElement(_)) => {
+            ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLTableCellElement) => {
                 LayoutElementType::HTMLTableCellElement
             },
             ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLTableColElement) => {