[runtime] Remove unused TO_NUMBER and TO_STRING functions.
[runtime] Remove unused TO_NUMBER and TO_STRING functions.

R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/1304363012

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#30507}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh