[3.11] gh-153030: Fix quadratic complexity in incremental parsing in HTMLParser (GH-153031) (#153042)
gh-153030: Fix quadratic complexity in incremental parsing in HTMLParser (GH-153031)
When an unterminated construct (e.g. a tag or comment) spanned many
feed() calls, rescanning the growing buffer and concatenating new data
onto it were both quadratic. New data is now accumulated in a list and
only joined and parsed once enough has piled up.
(cherry picked from commit bcf98ddbc40ec9b3ee87da0124a5660b19b7e606)
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>