Add WebAuthn bindings and client interface.

third_party/WebKit/Source/modules/webauthentication/WebAuthentication.idl

Index: third_party/WebKit/Source/modules/webauthentication/WebAuthentication.idl
diff --git a/third_party/WebKit/Source/modules/webauthentication/WebAuthentication.idl b/third_party/WebKit/Source/modules/webauthentication/WebAuthentication.idl
new file mode 100644
index 0000000000000000000000000000000000000000..5293fa82e9b4ae985caa47e3bf59da6e8a7493c4
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+++ b/third_party/WebKit/Source/modules/webauthentication/WebAuthentication.idl
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+// 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://w3c.github.io/webauthn/#webauthentication
+
+[
+    RuntimeEnabled=WebAuthentication,
+    SecureContext
+] interface WebAuthentication {
+    [CallWith=ScriptState] Promise<sequence<ScopedCredentialInfo>> makeCredential(Account accountInformation, sequence<ScopedCredentialParameters> cryptoParameters, BufferSource attestationChallenge, optional ScopedCredentialOptions options);
+    [CallWith=ScriptState] Promise<sequence<WebAuthnAssertion>> getAssertion(BufferSource assertionChallenge, optional AssertionOptions options);
+};