Start `query-replace' with string to replace from last search string.
The arg DELIMITED (prefix arg if interactive), if non-nil, means replace
only matches surrounded by word boundaries. Note that using the prefix arg
is possible only when `isearch-allow-scroll' is non-nil, and it doesn't
always provide the correct matches for `query-replace', so the preferred
way to run word replacements from Isearch is `M-s w ... M-%'.