Fix an index and clean up comments.
diff --git a/Lib/html/parser.py b/Lib/html/parser.py
index 9db8ab5..aa31fbc 100644
--- a/Lib/html/parser.py
+++ b/Lib/html/parser.py
@@ -270,12 +270,13 @@
         if rawdata[i:i+2] != '<!':
             self.error('unexpected call to parse_html_declaration()')
         if rawdata[i:i+4] == '<!--':
+            # this case is actually already handled in goahead()
             return self.parse_comment(i)
         elif rawdata[i:i+3] == '<![':
             return self.parse_marked_section(i)
         elif rawdata[i:i+9].lower() == '<!doctype':
             # find the closing >
-            gtpos = rawdata.find('>', 9)
+            gtpos = rawdata.find('>', i+9)
             if gtpos == -1:
                 return -1
             self.handle_decl(rawdata[i+2:gtpos])