init(): cache code.length

lib/b64.js

@@ -10,12 +10,13 @@ var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array
 function init () {
   var i
   var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
+  var len = code.length
 
-  for (i = 0; i < code.length; i++) {
+  for (i = 0; i < len; i++) {
     lookup[i] = code[i]
   }
 
-  for (i = 0; i < code.length; ++i) {
+  for (i = 0; i < len; ++i) {
     revLookup[code.charCodeAt(i)] = i
   }
   revLookup['-'.charCodeAt(0)] = 62