Conditional processing attributes should also be evaluated outside of <switch>
Currently, librsvg only considers conditional processing attributes when evaluating a <switch>
.
Per the spec on conditional processing, the attributes requiredExtensions
and systemLanguage
also need to be evaluated for elements that are not children of <switch>
- in that case, they are just booleans which determine whether the element is displayed or not ("When an element is excluded because of conditional processing, it is treated as if it had a used value of none for the display property").