Add :defined pseudo-class

Author: vrugtehagel

CSS3.sublime-syntax

@@ -11099,6 +11099,7 @@ contexts:
           in-range|
           hover|
           host|
+          defined|
           future|
           fullscreen|
           focus-within|

test/syntax_test_selectors.css

@@ -239,6 +239,11 @@
  /* <- entity.other.attribute-name.pseudo-class.css */
 /*^^^ entity.other.attribute-name.pseudo-class.css */
 /*   ^ -entity.other.attribute-name.pseudo-class.css */
+:defined {}
+/* <- entity.other.attribute-name.pseudo-class.css punctuation.definition.entity.pseudo-class.css */
+ /* <- entity.other.attribute-name.pseudo-class.css */
+/*^^^^^^ entity.other.attribute-name.pseudo-class.css */
+/*      ^ -entity.other.attribute-name.pseudo-class.css */
 :future {}
 /* <- entity.other.attribute-name.pseudo-class.css punctuation.definition.entity.pseudo-class.css */
  /* <- entity.other.attribute-name.pseudo-class.css */