xpointer(string-range(...)) matched the search string at every position
of each node's value and re-allocated the whole needle window per
position, an O(text * needle) search and a denial-of-service vector on a
long node value with a near-matching needle. Replace it with a
linear-time Knuth-Morris-Pratt search (failure function built once, since
the needle is fixed across nodes). Matches are unchanged: same
non-overlapping, left-to-right occurrences, same offset/length.
A near-matching needle over a 16000-character node drops from about
0.18 s to about 0.002 s (~100x), now linear.
Mihaela Mihaljevic
904881b81c