Add a UA style, "display: contents", for <slot>

third_party/WebKit/Source/core/css/slot.css

Index: third_party/WebKit/Source/core/css/slot.css
diff --git a/device/bluetooth/public/interfaces/uuid.mojom b/third_party/WebKit/Source/core/css/slot.css
similarity index 69%
copy from device/bluetooth/public/interfaces/uuid.mojom
copy to third_party/WebKit/Source/core/css/slot.css
index 90a1586565164b40e1ab4d8f1bd43c336960e46c..36bb6f6ae28f4442db28c46e8d9ca8ac93344f0e 100644
--- a/device/bluetooth/public/interfaces/uuid.mojom
+++ b/third_party/WebKit/Source/core/css/slot.css
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-module bluetooth.mojom;
+@namespace "http://www.w3.org/1999/xhtml";
 
-struct UUID {
-  string uuid;
-};
+slot {
+    display: contents;
+}