CSSMediaRule and CSSSupportsRule inherit from CSSConditionRule

third_party/WebKit/Source/core/css/CSSConditionRule.idl

Index: third_party/WebKit/Source/core/css/CSSConditionRule.idl
diff --git a/third_party/WebKit/Source/core/css/CSSConditionRule.idl b/third_party/WebKit/Source/core/css/CSSConditionRule.idl
new file mode 100644
index 0000000000000000000000000000000000000000..824a340d4bec55e3611c2bb3cd5cfe81877caac7
--- /dev/null
+++ b/third_party/WebKit/Source/core/css/CSSConditionRule.idl
@@ -0,0 +1,10 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// https://drafts.csswg.org/css-conditional/#the-cssconditionrule-interface
+
+interface CSSConditionRule : CSSGroupingRule {
+    // TODO(xing.xu): readonly should be removed.
+    readonly attribute DOMString conditionText;
+};