[dev.unified] cmd/compile/internal/reflectdata: prefer ITabAddrAt in ConvIfaceTypeWord

We already have an explicit `pos` parameter, so we should use
ITabAddrAt instead of ITabAddr (which uses `base.Pos` instead).

Change-Id: I7c8c5ae93d0ae7a6467cc972575cb547981576f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/415578
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/compile/internal/reflectdata/helpers.go

@@ -113,7 +113,7 @@ func ConvIfaceTypeWord(pos src.XPos, n *ir.ConvExpr) ir.Node {
 		return concreteRType(pos, src) // direct eface construction
 	}
 	if !src.IsInterface() {
-		return ITabAddr(src, dst) // direct iface construction
+		return ITabAddrAt(pos, src, dst) // direct iface construction
 	}
 	return TypePtrAt(pos, dst) // convI2I
 }