fix up test styling and add use-strict declarator

test/fixtures/syntax/classes/instance-method/expected.js

@@ -1,12 +1,17 @@
-var Test = function () {
-  var Test = function Test() { };
+"use strict";
+
+var Test = function() {
+  var Test = function Test() {};
+
   Object.defineProperties(Test.prototype, {
     test: {
       writable: true,
-      value: function () {
+
+      value: function() {
         return 5 + 5;
       }
     }
   });
+
   return Test;
-}();
+}();