Bug 1864896: Autofix unused function arguments (modules/libpref). r=KrisWright

Differential Revision: https://phabricator.services.mozilla.com/D202974

modules/libpref/test/browser/browser_sanitization_events.js

@@ -51,7 +51,7 @@ add_task(async function sanitized_pref_test() {
 
   await BrowserTestUtils.withNewTab(
     { gBrowser, url: PAGE_URL },
-    async function (browser) {}
+    async function () {}
   );
 
   // Needed because otherwise we advance too quickly

modules/libpref/test/unit/test_bug345529.js

@@ -9,7 +9,7 @@ function run_test() {
   var observer = {
     QueryInterface: ChromeUtils.generateQI(["nsIObserver"]),
 
-    observe: function observe(aSubject, aTopic, aState) {
+    observe: function observe() {
       Services.prefs.removeObserver(PREF_NAME, observer);
     },
   };

modules/libpref/test/unit/test_bug577950.js

@@ -6,7 +6,7 @@ function run_test() {
   var observer = {
     QueryInterface: ChromeUtils.generateQI(["nsIObserver"]),
 
-    observe: function observe(aSubject, aTopic, aState) {
+    observe: function observe() {
       // Don't do anything.
     },
   };