Use leven module for levenshtein distance

https://github.com/sindresorhus/leven

No point in bundling code like this.

Leven is also the fastest one: https://github.com/sindresorhus/leven#benchmark

lib/babel/helpers/levenshtein.js

@@ -1,38 +0,0 @@
-// taken from stackoverflow, it's crap i know.
-
-module.exports = function (a, b) {
-  if (a.length === 0) return b.length;
-  if (b.length === 0) return a.length;
-
-  var matrix = [];
-
-  // increment along the first column of each row
-  var i;
-  for (i = 0; i <= b.length; i++) {
-    matrix[i] = [i];
-  }
-
-  // increment each column in the first row
-  var j;
-  for (j = 0; j <= a.length; j++) {
-    matrix[0][j] = j;
-  }
-
-  // Fill in the rest of the matrix
-  for (i = 1; i <= b.length; i++) {
-    for (j = 1; j <= a.length; j++) {
-      if (b.charAt(i - 1) == a.charAt(j - 1)) {
-        matrix[i][j] = matrix[i - 1][j - 1];
-      } else {
-        matrix[i][j] = Math.min(
-          matrix[i - 1][j - 1] + 1, // substitution
-          Math.min(
-            matrix[i][j - 1] + 1, // insertion
-            matrix[i - 1][j] + 1) // deletion
-          );
-      }
-    }
-  }
-
-  return matrix[b.length][a.length];
-};

lib/babel/transformation/transformers/validation/undeclared-variable-check.js

@@ -1,6 +1,6 @@
 "use strict";
 
-var levenshtein = require("../../../helpers/levenshtein");
+var levenshtein = require("leven");
 var messages    = require("../../../messages");
 var t           = require("../../../types");
 

package.json

@@ -51,6 +51,7 @@
     "fs-readdir-recursive": "0.1.0",
     "globals": "^5.1.0",
     "js-tokenizer": "1.3.3",
+    "leven": "^1.0.1",
     "lodash": "3.0.0",
     "output-file-sync": "1.1.0",
     "private": "0.1.6",