LibJS/Tests: Remove fileName and lineNumber args from ExpectationError

This is nono-standard, not supported by our Error implementation and not
even used anywhere, so let's just remove it.

Userland/Libraries/LibJS/Tests/test-common.js

@@ -20,8 +20,8 @@ console.log = (...args) => {
 };
 
 class ExpectationError extends Error {
-    constructor(message, fileName, lineNumber) {
-        super(message, fileName, lineNumber);
+    constructor(message) {
+        super(message);
         this.name = "ExpectationError";
     }
 }