Pass the tag markup and tokenizer to Document#unknown_tag

The parse_context no longer needs to be passed in because it is available
through through an attr_reader on the instance. However, the markup and
tokenizer weren't made available.  This refactor also makes the parameters
given to Document#unknown_tag consistent with Block#unknown_tag.

lib/liquid/document.rb

@@ -19,16 +19,15 @@ module Liquid
       @body.nodelist
     end
 
-    def parse(tokens, parse_context)
-      @body.parse(tokens, parse_context) do |end_tag_name, _end_tag_params|
-        unknown_tag(end_tag_name, parse_context) if end_tag_name
+    def parse(tokenizer, parse_context)
+      while parse_body(tokenizer)
       end
     rescue SyntaxError => e
       e.line_number ||= parse_context.line_number
       raise
     end
 
-    def unknown_tag(tag, parse_context)
+    def unknown_tag(tag, _markup, _tokenizer)
       case tag
       when 'else', 'end'
         raise SyntaxError, parse_context.locale.t("errors.syntax.unexpected_outer_tag", tag: tag)
@@ -50,5 +49,16 @@ module Liquid
     def new_body
       parse_context.new_block_body
     end
+
+    def parse_body(tokenizer)
+      @body.parse(tokenizer, parse_context) do |unknown_tag_name, unknown_tag_markup|
+        if unknown_tag_name
+          unknown_tag(unknown_tag_name, unknown_tag_markup, tokenizer)
+          true
+        else
+          false
+        end
+      end
+    end
   end
 end