Define XSLTProcessor #181
These are the surface-level differences between Gecko and Blink that I added as TODOs in our IDL file:
For the error handling, I think it probably doesn't matter much for compat if we return null or throw an exception. For parameter values, supporting any value type would be slightly more code, and since it's apparently not needed for compat I think just DOMString would be better.
This is the use counter data for Chrome:
Both are so low that there's a good chance for some simplification if this is spec'd from scratch.