[playground] Only collect first level of function declarations

#1433 means that Forget now will compile nested function declarations, so we no 
longer need to compile these separately

compiler/forget/packages/playground/components/Editor/index.tsx

@@ -57,6 +57,7 @@ function parseFunctions(
       FunctionDeclaration: {
         enter(nodePath) {
           items.push(nodePath);
+          nodePath.skip();
         },
       },
     });