LWG3811 views::as_const on ref_view<T> should return ref_view<const T>

Author: burblebee

source/ranges.tex

@@ -8630,6 +8630,11 @@
 then \tcode{span<const X, Extent>(E)}.
 \item
 Otherwise,
+if \tcode{U} denotes \tcode{ref_view<X>} for some type \tcode{X} and
+\tcode{const X} models \libconcept{constant_range},
+then \tcode{ref_view(static_cast<const X\&>(E.base()))}.
+\item
+Otherwise,
 if \tcode{E} is an lvalue,
 \tcode{const U} models \libconcept{constant_range}, and
 \tcode{U} does not model \libconcept{view},