Comment Spelling [ci skip]

jszip.js

@@ -329,9 +329,9 @@ DataReader.prototype = {
         // see implementations
     },
     /**
-     * Find the last occurence of a zip signature (4 bytes).
+     * Find the last occurrence of a zip signature (4 bytes).
      * @param {string} sig the signature to find.
-     * @return {number} the index of the last occurence, -1 if not found.
+     * @return {number} the index of the last occurrence, -1 if not found.
      */
     lastIndexOfSignature: function(sig) {
         // see implementations