(isearch-lazy-highlight-new-loop):

(isearch-lazy-highlight-new-loop):
Make arguments beg and end optional.
(isearch-update): Remove optional arguments nil from
isearch-lazy-highlight-new-loop.
(isearch-lazy-highlight-search): Let-bind case-fold-search to
isearch-lazy-highlight-case-fold-search instead of
isearch-case-fold-search, and let-bind isearch-regexp to
isearch-lazy-highlight-regexp.  Use
isearch-lazy-highlight-last-string instead of isearch-string.