Check for recommended browser version

Also removed Vivaldi from the rejected list to match gui

src/l10n.json

@@ -103,7 +103,7 @@
     "general.teacherAccounts": "Teacher Accounts",
 
     "general.unsupportedBrowser": "This browser is not supported",
-    "general.unsupportedBrowserDescription": "We're very sorry, but Scratch 3.0 does not support Internet Explorer, Vivaldi, Opera or Silk. We recommend trying a newer browser such as Google Chrome, Mozilla Firefox, or Microsoft Edge.",
+    "general.unsupportedBrowserDescription": "We are very sorry, but Scratch does not support this browser version. We recommend updating to the latest version of a supported browser such as Google Chrome, Mozilla Firefox, Microsoft Edge, or Apple Safari.",
     "general.3faq": "To learn more, go to the {faqLink}.",
 
     "footer.discuss": "Discussion Forums",

src/lib/supported-browser.js

@@ -6,10 +6,18 @@ import bowser from 'bowser';
  */
 export default function () {
     if (bowser.msie ||
-        bowser.vivaldi ||
         bowser.opera ||
         bowser.silk) {
         return false;
     }
-    return true;
+    // IMPORTANT: If you change versions here, also change them in gui
+    // minimum versions for recommended browsers
+    const minVersions = {
+        chrome: '63',
+        msedge: '15',
+        firefox: '57',
+        safari: '11'
+    };
+    // strict mode == false so any browser not mentioned in the min Versions is ok
+    return !bowser.isUnsupportedBrowser(minVersions, false);
 }