Previous attempt tried to break the dataflow by reconstructing the
close-fence regex from a literal char + marker.length, but CodeQL still
traced marker.length back to input and kept flagging the test-fixture
URLs as hostname-regex sources (js/incomplete-hostname-regexp).
Replace `new RegExp(...)` + `closeRe.test(body)` with a string-only
hasCloseFenceLine() helper that splits on '\n' and uses ===. No regex
on this path now, so input data can no longer reach a RegExp source.
Behavior preserved: matches lines that are (whitespace + marker +
whitespace), which is what the original `\n[ \t]*${marker}[ \t]*(?=\n|$)`
matched. All 12 markdown-text tests still pass.
Brooklyn Nicholson
d37ea68822