IDL compiler: [RaisesException] on interface type attributes

15 => 12

BUG=239771
R=haraken
NOTRY=true

Review URL: https://codereview.chromium.org/131453010

git-svn-id: svn://svn.chromium.org/blink/trunk@166453 bbb929c8-8fbe-4397-9dbb-9b2b20218538