WPT details: Tests are added in https://chromium-review.googlesource.com/c/chromium/src/+/4061476 However, advanced parsing such as checking the max limits 1000 and 65534 defined in HTML is a bit tedious as MathML does not have an IDL for tables yet ( https://github.com/w3c/mathml-core/issues/166#issuecomment-1411721093 ) so for now they are written as internal tests.
Implement attributes to specify the number of columns and rows that a MathML table cell is to span. This is similar to HTML colspan/rowspan attributes and does not have equivalent CSS properties.