Reuse view_context_class when possible

The generated view context classes tend to be fairly complex and use a
lot of memory. Similar to how we only generate new helper classes when
necessary (see #40204) we should be
doing the same for view context classes.

actionview/lib/action_view/rendering.rb

@@ -48,7 +48,18 @@ def _routes
       def _helpers
       end
 
+      def inherit_view_context_class?
+        superclass.respond_to?(:view_context_class) &&
+          supports_path? == superclass.supports_path? &&
+          _routes.equal?(superclass._routes) &&
+          _helpers.equal?(superclass._helpers)
+      end
+
       def build_view_context_class(klass, supports_path, routes, helpers)
+        if inherit_view_context_class?
+          return superclass.view_context_class
+        end
+
         Class.new(klass) do
           if routes
             include routes.url_helpers(supports_path)