Reading about code checker in https://moodle.org/mod/forum/discuss.php?d=244921#p1062134 I realized that I made an error when submitting the MDL-39810 PR for 2.6: I've used $compat_view instead of $compatview.

The 2.5 branch, though affected by a similar issue, should not be modified because of $supports_json_contenttype is more readable than $supportsjsoncontenttype and, at that time, I tried to mimic the new function introduced in 2.6+, core_useragent::supports_json_contenttype().