Fix :element selector without element type

lib/capybara/selector.rb

@@ -460,7 +460,7 @@ end
 
 Capybara.add_selector(:element) do
   xpath do |locator, **|
-    XPath.descendant((locator || '@').to_sym)
+    locator ? XPath.descendant(locator.to_sym) : XPath.descendant
   end
 
   expression_filter(:attributes, matcher: /.+/) do |xpath, name, val|

spec/selector_spec.rb

@@ -261,6 +261,10 @@ RSpec.describe Capybara do
           expect { string.all(:element, 'input', type: 'submit', count: 1) }.not_to raise_error
         end
 
+        it 'works without element type' do
+          expect(string.find(:element, type: 'submit').value).to eq 'click me'
+        end
+
         it 'includes wildcarded keys in description' do
           expect { string.find(:element, 'input', not_there: 'bad', count: 1) }
             .to(raise_error do |e|