Fix IteratorNext intrinsic to cast its dispatch receiver to

the expected type.

^KT-47741 Fixed.

compiler/testData/codegen/box/callableReference/function/kt47741.kt

@@ -0,0 +1,6 @@
+// IGNORE_BACKEND: WASM
+
+fun box(): String {
+   val generateId = (1 .. Int.MAX_VALUE).iterator()::next
+   return if (generateId() == 1) "OK" else "FAIL"
+}