CodeHealth: Remove use of Value::GetAsInteger

This change removes the use of Value::GetAsInteger and replaces with
Value::is_int(), Value::GetInt(), Value::GetIfInt().

Bug: 1187004
Change-Id: Ia472ded71b492d31b80c92f0fde1ef4a3b7c0ff1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2825536


Reviewed-by: Ramin Halavati <rhalavati@chromium.org>
Commit-Queue: Minoru Chikamune <chikamune@chromium.org>
Cr-Commit-Position: refs/heads/master@{#872383}