Add verwaest as an API owner

Previous API owners (adamk, yangguo) are less-involved with the JS API
then ever, so it seems appropriate to have an owner whose responsibility
is squarely in the JS domain.

Change-Id: I4235778fda8f55d0429e875d52ff74049024dad1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1860328Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64300}

include/OWNERS

 adamk@chromium.org
 danno@chromium.org
 ulan@chromium.org
+verwaest@chromium.org
 yangguo@chromium.org
 
 per-file *DEPS=file:../COMMON_OWNERS