fix browser version

browser/fs.js

@@ -1,6 +1,7 @@
 const nope = method => `Cannot use fs.${method} inside browser`;
 
-export const isFile = () => false;
+export const lstatSync = nope( 'lstatSync' );
 export const readdirSync = nope( 'readdirSync' );
 export const readFileSync = nope( 'readFileSync' );
+export const realpathSync = nope( 'realpathSync' );
 export const writeFile = nope( 'writeFile' );