Fix cycle tag

- `respond_to?` was returning `false` in the parser switcher
     because `rigid_parse` was private
     It was working before because `parse_context` was doing
     the double-parsing thing, but when we removed that, this
     test fairly started breaking

lib/liquid/tags/cycle.rb

@@ -52,8 +52,6 @@ module Liquid
       output
     end
 
-    private
-
     # cycle [name:] expression(, expression)*
     def rigid_parse(markup)
       p = @parse_context.new_parser(markup)
@@ -73,6 +71,8 @@ module Liquid
       raise_syntax_error(options) if @variables.empty?
     end
 
+    private
+
     # Temporarily until we migrate
     def strict_parse(markup)
       lax_parse(markup)

test/integration/tags/cycle_tag_test.rb

@@ -55,10 +55,9 @@ class CycleTagTest < Minitest::Test
       end
     end
 
-    skip("todo(guilherme): parse_context.safe_parse_expression in progress...")
-    # with_error_mode(:rigid) do
-    #   assert_raises(Liquid::SyntaxError) { Template.parse("{% cycle .5: 'a', 'b' %}") }
-    #   assert_raises(Liquid::SyntaxError) { Template.parse("{% cycle .5, .4 %}") }
-    # end
+    with_error_mode(:rigid) do
+      assert_raises(Liquid::SyntaxError) { Template.parse("{% cycle .5: 'a', 'b' %}") }
+      assert_raises(Liquid::SyntaxError) { Template.parse("{% cycle .5, .4 %}") }
+    end
   end
 end