IDL compiler: Special interfaces configuration

30 => 27

BUG=239771
R=haraken
NOTRY=true

Review URL: https://codereview.chromium.org/133373004

git-svn-id: svn://svn.chromium.org/blink/trunk@166380 bbb929c8-8fbe-4397-9dbb-9b2b20218538