internal/export/idna: added benchmark

Change-Id: Ifd8572aa15f1936c5532fe27f38a6067650ca73c
Reviewed-on: https://go-review.googlesource.com/63793
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>

internal/export/idna/idna_test.go

diff --git a/internal/export/idna/idna_test.go b/internal/export/idna/idna_test.go
index 137bbac..fed6e2e 100644
--- a/internal/export/idna/idna_test.go
+++ b/internal/export/idna/idna_test.go
@@ -300,3 +300,9 @@
 	}
 	return s
 }
+
+func BenchmarkProfile(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Lookup.ToASCII("www.yahoogle.com")
+	}
+}