[geometry] DOMMatrix parsing does not describe how to handle percentages

[AtkinsSJ]

https://drafts.fxtf.org/geometry/#ref-for-typedef-transform-list

If parsedValue is failure, or any <transform-function> has <length> values without absolute length units, or any keyword other than none is used, then return failure.

<percentage> values appear in some transform-function definitions:

1. In Transforms-1, the translate() functions have <length-percentage> parameters. A percentage here needs to be rejected like a non-absolute length, since it cannot be resolved without an element.

2. In Transforms-2, the scale() functions are modified to accept <percentage> parameters that are equivalent to numbers, so these can be resolved.

Case 2 could be handled during parsing so may not be an issue. But I believe case 1 does need to be covered here.