This function should also be callable from a concurrent thread, so we cannot use
the scope here. Instead, provide a test that checks that no handles are created.

R=ulan@chromium.org
TEST=cctest/test-conversions/NoHandlesForTryNumberToSize
BUG=

Review-Url: https://codereview.chromium.org/2106083002
Cr-Commit-Position: refs/heads/master@{#37381}