Position/Dimension Attributes as Strings breaks transforms

[adam-james-v]

When importing SVG files, there may be valid SVG that stores dimensions as strings. The transform functions all expect numbers and so if a dimension attribute stores the value in a string, the functions fail.

This is not noticed when generating elements from within the library, but can easily show up when a user styles things manually, creates their own element generating functions, or imports SVGs from other sources.

This was initially recognized when investigating a question from this discussion.