Remove redundant Name from IntOp nodes

[Blaisorblade]

This name was needed when arithmetic operations were just functions, but they were defunctionalized in 9d2adccc3308ccefa5d1215c1a041b1d70f5af8a.

This prevents inconsistencies between the two representations of the operation; the current code just avoided them by being careful.

[Blaisorblade]

I annotated the places which might less boring — the rest of the patch looks entirely mechanical to me.