decode regex if needed

[dylan-conway]

What does this PR do?

fixes #5132

• Documentation or TypeScript types (it's okay to leave the rest blank in this case)
• Code changes

How did you verify your code works?

added test and tested manually.

[github-actions]

❌ @dylan-conway 3 files with test failures on bun-darwin-aarch64:

• test/js/bun/spawn/spawn.test.ts
• test/js/bun/test/test-test.test.ts
• test/js/node/watch/fs.watch.test.ts

View test output

^{#5c467060976df3c3e8c3345a10c25a8880e4a755}

[github-actions]

❌ @dylan-conway 1 files with test failures on linux-x64-baseline:

• test/js/web/fetch/fetch-gzip.test.ts

View test output

^{#5c467060976df3c3e8c3345a10c25a8880e4a755}

[github-actions]

✅ test failures on linux-x64 have been resolved.

^{#5c467060976df3c3e8c3345a10c25a8880e4a755}

[github-actions]

❌ @dylan-conway 4 files with test failures on bun-darwin-x64-baseline:

• test/js/bun/sqlite/sqlite.test.js
• test/js/node/fs/fs.test.ts
• test/js/third_party/webpack/webpack.test.ts
• test/js/web/timers/setTimeout.test.js

View test output

^{#5c467060976df3c3e8c3345a10c25a8880e4a755}