return comment to deterministicK

lib/crypto/ecdsa.js

@@ -75,6 +75,9 @@ ECDSA.prototype.randomK = function() {
 // https://tools.ietf.org/html/rfc6979#section-3.2
 ECDSA.prototype.deterministicK = function(badrs) {
   /* jshint maxstatements: 25 */
+  // if r or s were invalid when this function was used in signing,
+  // we do not want to actually compute r, s here for efficiency, so,
+  // we can increment badrs. explained at end of RFC 6979 section 3.2
   if (_.isUndefined(badrs)) {
     badrs = 0;
   }