(isearch-set-lazy-highlight-faces-at): New function.

(isearch-set-lazy-highlight-faces-at): New function.
(isearch-highlight): Restore lazy-isearch face properties at old
  position, and suppress them at new position.
(isearch-dehighlight): Restore lazy-isearch face properties.
(isearch-lazy-highlight-update): Add lazy-isearch overlays even
  over the real isearch overlay, but in that case, don't give it a
  face property.  Use `push'.