cmd/compile/internal/ssa: fix `a == a` to `a == b`

Change-Id: I4ee4f702e1bfc9ad9ea899c255104d5e18cf2c96
Reviewed-on: https://go-review.googlesource.com/135838Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/ssa/html.go

@@ -484,7 +484,7 @@ func (x ByTopo) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
 func (x ByTopo) Less(i, j int) bool {
 	a := x[i]
 	b := x[j]
-	if a.Filename == a.Filename {
+	if a.Filename == b.Filename {
 		return a.StartLineno < b.StartLineno
 	}
 	return a.Filename < b.Filename