Selector cache hit rate falls from 100% to 0% at CACHE_LIMIT + 1 under jsdom's stylesheet scan (2.2.25+); #185/#186 are not in master #242

Since 2.2.25 the compiled-selector caches are a strict LRU bounded at CACHE_LIMIT = 1000 (2.2.28 src/nwsapi.js:236, eviction at :290). jsdom's getComputedStyle matches every stylesheet rule against each element in sheet order, which is a loop. On a loop of N > limit selectors, LRU always evicts the one the scan needs next, so the hit rate drops from 100% to 0% at N = limit + 1 and every match recompiles. A page carrying antd's CSS-in-JS has about 2,300 rules. One of our jsdom test files went from 3.7 s on 2.2.22 to a 37 s timeout on 2.2.28, with about 1.05M recompiles. With the limit raised to 1e6 it runs in 6.8 s.

Reproducer (npm i jsdom nwsapi@2.2.28):

const { JSDOM } = require('jsdom'), nwsapi = require('nwsapi');
for (const N of [1000, 1001]) {
  const { window } = new JSDOM('<p class="c0">'), el = window.document.querySelector('p');
  const nw = nwsapi({ document: window.document, DOMException: window.DOMException });
  const sels = Array.from({ length: N }, (_, i) => `.c${i}`);
  sels.forEach(s => nw.match(s, el)); // first pass compiles each selector once
  let miss = 0;
  for (let pass = 0; pass < 10; pass++) for (const s of sels) { miss += !nw.matchResolvers.has(s); nw.match(s, el); }
  console.log(`${N} selectors: ${miss} cache misses in ${N * 10} matches`);
}

Output: 1000 selectors: 0 cache misses in 10000 matches, then 1001 selectors: 10010 cache misses in 10010 matches.

#185 (two-generation eviction) and #186 (limit 4096) were merged on 2026-09-07, but neither merge commit is in current master or in 2.2.28. Master (8b622b5) also adds CACHE_BYTES = 2 MB, which evicts from the same head. Even with the entry limit at 100,000, selectors shaped like :where(.css-x).ant-btn-N:not(:disabled):not(.ant-btn-disabled):hover miss on every match from N = 1,254.

Could the next 2.2.x (a) restore bounds that cover a real stylesheet, or let the host set them (jsdom already calls configure(), which accepts only booleans today), and (b) evict so that a scan larger than the cache keeps a resident subset hitting instead of none?