re. #2550: just implement the logic used to solve https://bugs.chromium.org/p/chromium/issues/detail?id=683314

src/js/popup.js

@@ -97,12 +97,14 @@ var domainsHitStr = vAPI.i18n('popupHitDomainCount');
 
 // https://github.com/gorhill/uBlock/issues/2550
 // Solution inspired from
+// - https://bugs.chromium.org/p/chromium/issues/detail?id=683314
 // - https://bugzilla.mozilla.org/show_bug.cgi?id=1332714#c17
 // Confusable character set from:
 // - http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5B%D0%B0%D1%81%D4%81%D0%B5%D2%BB%D1%96%D1%98%D3%8F%D0%BE%D1%80%D4%9B%D1%95%D4%9D%D1%85%D1%83%D1%8A%D0%AC%D2%BD%D0%BF%D0%B3%D1%B5%D1%A1%5D&g=gc&i=
 // Linked from:
 // - https://www.chromium.org/developers/design-documents/idn-in-google-chrome
-var reAmbiguousIDN = /^[a-zасԁеһіјӏорԛѕԝхуъЬҽпгѵѡ.-]+$/;
+var reCyrillicNonAmbiguous = /[\u0400-\u042b\u042d-\u042f\u0431\u0432\u0434\u0436-\u043d\u0442\u0444\u0446-\u0449\u044b-\u0454\u0457\u0459-\u0460\u0462-\u0474\u0476-\u04ba\u04bc\u04be-\u04ce\u04d0-\u0500\u0502-\u051a\u051c\u051e-\u052f]/;
+var reCyrillicAmbiguous = /[\u042c\u0430\u0433\u0435\u043e\u043f\u0440\u0441\u0443\u0445\u044a\u0455\u0456\u0458\u0461\u0475\u04bb\u04bd\u04cf\u0501\u051b\u051d]/;
 
 /******************************************************************************/
 
@@ -210,11 +212,11 @@ var addFirewallRow = function(des) {
         isDomain = des === hnDetails.domain,
         prettyDomainName = punycode.toUnicode(des),
         isPunycoded = prettyDomainName !== des;
-
     var span = row.nodeAt(0).querySelector('span:first-of-type');
     span.classList.toggle(
         'isIDN',
-        isDomain && isPunycoded && reAmbiguousIDN.test(prettyDomainName)
+        isPunycoded && reCyrillicAmbiguous.test(prettyDomainName) === true &&
+                       reCyrillicNonAmbiguous.test(prettyDomainName) === false
     );
     span.querySelector('span').textContent = prettyDomainName;
     span.title = isDomain && isPunycoded ? des : '';