A method-reference argument is passed by address on 32-bit targets

Found by the Pascal cross-target differential (both tests green natively).

Resolution (2026-09-28)

The methodref arm still materialises the pair with IRMethodRefToTemp, and when the parameter is not by reference (not isRefArg -- the pair fits the by-value band) it passes the temp's value with an IR_LOAD_SYM tagged tyRecord, exactly the node Call(f) over a variable lowers to. 64-bit targets, where the 16-byte pair is promoted to by-ref, are unchanged. Both tests now run cross in test-core.