Add WebUSB bindings and client interface

Source/modules/webusb/USBEndpoint.idl

Index: Source/modules/webusb/USBEndpoint.idl
diff --git a/Source/modules/webusb/USBEndpoint.idl b/Source/modules/webusb/USBEndpoint.idl
new file mode 100644
index 0000000000000000000000000000000000000000..29fa8923ab80ef7b31885b505e7f1dc2a5e1fe78
--- /dev/null
+++ b/Source/modules/webusb/USBEndpoint.idl
@@ -0,0 +1,24 @@
+// 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.
+
+enum USBDirection {
+    "in",
+    "out"
+};
+
+enum USBEndpointType {
+    "bulk",
+    "interrupt",
+    "isochronous"
+};
+
+[
+    GarbageCollected,
+    RuntimeEnabled=WebUSB,
+] interface USBEndpoint {
+    readonly attribute octet endpointNumber;
+    readonly attribute USBDirection direction;
+    readonly attribute USBEndpointType type;
+    readonly attribute unsigned long packetSize;
+};