FxAccountClient.js

  FxAccountClient.prototype._passwordChangeFinish = function(email, newPassword, oldCreds) {
    var self = this;
    var newWrapKb;
    var authPW;
    var oldWrapKB;

    var p1 = this.accountKeys(oldCreds.keyFetchToken, oldCreds.oldUnwrapBKey);
    var p2 = credentials.setup(email, newPassword);
    var p3 = hawkCredentials(oldCreds.passwordChangeToken, 'passwordChangeToken',  2 * 32);
    Promise.all([p1, p2, p3])
      .then(function(results) {
        var keys = results[0];
        var newCreds = results[1];
        var hawkCreds = results[2];
        var newWrapKb = sjcl.codec.hex.fromBits(
          credentials.xor(keys.kB, newCreds.unwrapBKey)
        );
        return self.request.send('/password/change/finish', 'POST', hawkCreds, {
          wrapKb: newWrapKb,
          authPW: sjcl.codec.hex.fromBits(newCreds.authPW)
        });
      });
  };

Promise.all([p1, p2, p3]) -> P.all([p1, p2, p3])