Highlight by name parameters at call site (#1000989)

Note that to decide if CallByNameParameter is merely defined or actually called, we cannot rely on the Symbol alone. To deal with this, handleCallByNameParamSpecialCase(...) also considers the associated tree.

I don't know if this is the kind of implementation you had in mind, but it seems to work at far as I can tell. Please tell me what you think.
I'm wondering about this distinction. We don't seem to do that for any other parameters. Do you think it's not going to be too confusing?