cmd/compile: add interface equality tests

Add interfaces which differ in type. Those used so far only
differ in value, not type.

These additional tests are needed to generate a failure
before CL 236278 went in.

Update #8606

Change-Id: Icdb7647b1973c2fff7e5afe2bd8b8c1b384f583e
Reviewed-on: https://go-review.googlesource.com/c/go/+/236418
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
diff --git a/test/fixedbugs/issue8606.go b/test/fixedbugs/issue8606.go
index 676c06c..8122b1d 100644
--- a/test/fixedbugs/issue8606.go
+++ b/test/fixedbugs/issue8606.go
@@ -22,6 +22,10 @@
 		{true, A{[]byte{1}, 1}, A{[]byte{1}, 2}},
 		{false, S{1, []byte{1}}, S{2, []byte{1}}},
 		{true, S{[]byte{1}, 1}, S{[]byte{1}, 2}},
+		{false, A{1, []byte{1}}, A{"2", []byte{1}}},
+		{true, A{[]byte{1}, 1}, A{[]byte{1}, "2"}},
+		{false, S{1, []byte{1}}, S{"2", []byte{1}}},
+		{true, S{[]byte{1}, 1}, S{[]byte{1}, "2"}},
 	} {
 		f := func() {
 			if test.a == test.b {