The Object.getOwnPropertyNames method always calls into C++ anyway,
so there's no point in having the JavaScript wrapper around at all.

Drive-by-fix: Inline GetOwnEnumerablePropertyNames into its single
call site.

CQ_INCLUDE_TRYBOTS=tryserver.chromium.win:win_chromium_rel_ng
R=yangguo@chromium.org

Committed: https://crrev.com/bf027fe756f62b4abcac8aa08134c8c5ed055620
Cr-Commit-Position: refs/heads/master@{#33380}

Review URL: https://codereview.chromium.org/1605803002

Cr-Commit-Position: refs/heads/master@{#33417}