fix up test styling and add use-strict declarator

test/fixtures/syntax/let-scoping/nested-function-2/exec.js

@@ -1,6 +1,6 @@
 function nestedFunction2() {
   let let_func = function() {
-    let let_x = 'let x';
+  let let_x = 'let x';
   }
   return let_func;
 }