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..dfbe96e95a115a839aa5e00f4d1867e41a9cde8b
--- /dev/null
+++ b/Source/modules/webusb/USBEndpoint.idl
@@ -0,0 +1,26 @@
+// 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"
+};
+
+[
+    Constructor(USBAlternateInterface alternate, octet endpointIndex),
+    RaisesException=Constructor,
+    GarbageCollected,
+    RuntimeEnabled=WebUSB,
+] interface USBEndpoint {
+    readonly attribute octet endpointNumber;
+    readonly attribute USBDirection direction;
+    readonly attribute USBEndpointType type;
+    readonly attribute unsigned long packetSize;
+};