Issue 4580 - Replace ext.getURL with extension.getURL

lib/options.js

Index: lib/options.js
===================================================================
--- a/lib/options.js
+++ b/lib/options.js
@@ -32,17 +32,17 @@
   {
     // We find a tab ourselves because Edge has a bug when quering tabs with
     // extension URL protocol:
     // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/8094141/
     // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/8604703/
     // Firefox won't let us query for moz-extension:// pages either, though
     // starting with Firefox 56 an extension can query for its own URLs:
     // https://bugzilla.mozilla.org/show_bug.cgi?id=1271354
-    let fullOptionsUrl = ext.getURL(optionsUrl);
+    let fullOptionsUrl = chrome.extension.getURL(optionsUrl);
     callback(tabs.find(element => element.url == fullOptionsUrl));
   });
 }
 
 function returnShowOptionsCall(optionsTab, callback)
 {
   if (!callback)
     return;