If a field and method have the same name, mark the respective struct field
so that we don't report follow-on errors when the field/method is accessed.
Per suggestion of @mdempsky.
Fixes#28268.
Change-Id: Ia1ca4cdfe9bacd3739d1fd7ca5e014ca094245ee
Reviewed-on: https://go-review.googlesource.com/c/144259
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
