In the channel-send case, the value to be sent may needs an
    (implicit) type conversion to the channel element type. This CL
    ensures that we use the correct value type for the send.
    
    Fixes golang/go#33235.
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/187177

From-SVN: r273743