Fix A-label bug

Author: jdesrosiers

#/tests/0/95.json

@@ -0,0 +1,6 @@
+{
+    "description": "MIDDLE DOT with surrounding 'l's as A-Label",
+    "comment": "https://tools.ietf.org/html/rfc5891#section-4.2.3.3 https://tools.ietf.org/html/rfc5892#appendix-A.3",
+    "data": "xn--ll-0ea",
+    "valid": true
+}

index.js

@@ -80,7 +80,7 @@ function isIdnHostname(hostname) {
             } catch (e) {
                 throwPunycodeError(`Invalid ASCII Compatible Encoding (ACE) of label '${rawLabel}' (RFC 5891 §4.4 → RFC 3492).`);
             }
-            if (/[\p{ASCII}]/u.test(label)) throwIdnaSyntaxError(`decoded A-label '${rawLabel}' result U-label '${label}' cannot be empty or all-ASCII character(s) (RFC 5890 §2.3.2.1).`);
+            if (!/[^\p{ASCII}]/u.test(label)) throwIdnaSyntaxError(`decoded A-label '${rawLabel}' result U-label '${label}' cannot be empty or all-ASCII character(s) (RFC 5890 §2.3.2.1).`);
             if (punycode.encode(label) !== aceBody) throwPunycodeError(`Re-encode mismatch for ASCII Compatible Encoding (ACE) label '${rawLabel}' (RFC 5891 §4.4 → RFC 3492).`);
         }
         // mapping phase (here because decoded A-label may contain disallowed chars)