This forces the call of the map view's display link target when the
display link is created. When a map view is shown the first time
this is not required. However, if the display link was torn down
and then recreated due to the map view being removed / obscured in the
view hierarchy the map view delegate may expect to be informed when
the map view did finish loading the map when it is shown again.
This adds a call to `updateFromDisplayLink` just after a display link
is created which helps trigger a full refresh of the map in the sense
that all delegate methods get exercised including
`mapViewDidFinishLoadingMap`.
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