This directory holds yarn lock file for kotlin js / wasm js. The offline mirror is located at prebuilts/external/androidx/javascript-for-kotlin.
To update the prebuilts and lockfile, run ./gradlew kotlinNpmInstall kotlinWasmNpmInstall -Pandroidx.yarnOfflineMode=false && ./gradlew kotlinUpgradeYarnLock kotlinWasmUpgradeYarnLock. You will need to upload changes from the prebuilts/external/androidx/javascript-for-kotlin together with changes to the lockfiles in frameworks/support.