test: add another test case for #35518

Updates #35518.

Change-Id: Icd052c8c68aae32696b5831a29e04cc4cb224b06
Reviewed-on: https://go-review.googlesource.com/c/go/+/206820
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

test/fixedbugs/issue35518.go

@@ -34,3 +34,11 @@ func f2() {
 	m := n2 // ERROR "."
 	sink = &m
 }
+
+func f3() {
+	var n1, n2 Node // ERROR "."
+	n1.Orig = &n1
+	n1.Orig = &n2
+
+	sink = n1.Orig.Orig
+}