Add WebUSB bindings and client interface

Source/modules/webusb/USBConfiguration.idl

Index: Source/modules/webusb/USBConfiguration.idl
diff --git a/Source/modules/webusb/USBConfiguration.idl b/Source/modules/webusb/USBConfiguration.idl
new file mode 100644
index 0000000000000000000000000000000000000000..123205eecacba2316007fb0c43507a6f7648b8ea
--- /dev/null
+++ b/Source/modules/webusb/USBConfiguration.idl
@@ -0,0 +1,12 @@
+// Copyright 2015 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.
+
+[
+    GarbageCollected,
+    RuntimeEnabled=WebUSB,
+] interface USBConfiguration {
+    readonly attribute octet configurationValue;
+    readonly attribute DOMString? configurationName;
+    readonly attribute sequence<USBInterface> interfaces;
+};