This removes all implicit casts and many implicit uses of dynamic. It
adds a gratuitous number of explicit "as" casts and arguably makes the
code worse.
This is an interim step towards replacing the big configuration map
with an actual typed object. These "as" casts should help catch places
where the configuration object is being used and where the code will
need to be changed to use a new object.
R=sigmund@google.com
Review-Url: https://codereview.chromium.org/2903703002 .
Bob Nystrom