internal/export/idna: fix typo

Change-Id: If3f6256085cd3342d2ab47802933ad48f36b4df1
Reviewed-on: https://go-review.googlesource.com/75450
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/internal/export/idna/idna.go b/internal/export/idna/idna.go
index fd8f3bd..e653c33 100644
--- a/internal/export/idna/idna.go
+++ b/internal/export/idna/idna.go
@@ -309,7 +309,7 @@
 		for ; len(s) > 0 && s[0] == '.'; s = s[1:] {
 		}
 	}
-	// TODO: allow for a quick check the tables data.
+	// TODO: allow for a quick check of the tables data.
 	// It seems like we should only create this error on ToASCII, but the
 	// UTS 46 conformance tests suggests we should always check this.
 	if err == nil && p.verifyDNSLength && s == "" {