String: replace, search, match now work with either string or regex
arg. Regex path uses js-string-index-of on source (case-adjusted
when ignoreCase set).
Array.from(iter, mapFn?) normalizes via js-iterable-to-list and
optionally applies mapFn.
Fixed dict-set! on list bug in js-regex-stub-exec — just omit the
index/input metadata, spec-breaking but tests that just check [0]
work.
407/409 unit (+8), 148/148 slice unchanged.
giles
60bb7c4687