cssom: add the CSSContainerRule interface

Author: carlosame

cssom-api/src/main/java/org/w3c/css/om/CSSContainerRule.java

@@ -0,0 +1,22 @@
+/*
+ * This software extends interfaces defined by CSS Conditional Rules Module Level 5
+ *  (https://drafts.csswg.org/css-conditional-5/).
+ * Copyright © 2013 W3C® (MIT, ERCIM, Keio, Beihang).
+ * https://www.w3.org/Consortium/Legal/2015/copyright-software-and-document
+ */
+/* 
+ * SPDX-License-Identifier: W3C-20150513
+ */
+
+package org.w3c.css.om;
+
+/**
+ * Represents a ‘{@literal @}container’ rule.
+ */
+public interface CSSContainerRule extends CSSConditionRule {
+
+	String getContainerName();
+
+	String getContainerQuery();
+
+}