ICSSCombinator: should extend ICSSNode, like other CSS interfaces

CSSCombinator extends CSSNodeBase, for reference
diff --git a/compiler/src/main/java/org/apache/royale/compiler/css/ICSSCombinator.java b/compiler/src/main/java/org/apache/royale/compiler/css/ICSSCombinator.java
index b68f257..debe31d 100644
--- a/compiler/src/main/java/org/apache/royale/compiler/css/ICSSCombinator.java
+++ b/compiler/src/main/java/org/apache/royale/compiler/css/ICSSCombinator.java
@@ -30,7 +30,7 @@
  * "descendant" (space character) and the combined selector is
  * {@code s|Button.rounded}.
  */
-public interface ICSSCombinator
+public interface ICSSCombinator extends ICSSNode
 {
 
     /**