Appease the types

src/components/views/elements/Tooltip.tsx

@@ -2,7 +2,7 @@
 Copyright 2015, 2016 OpenMarket Ltd
 Copyright 2019 New Vector Ltd
 Copyright 2019 Michael Telatynski <7t3chguy@gmail.com>
-Copyright 2019 The Matrix.org Foundation C.I.C.
+Copyright 2019, 2020 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -31,11 +31,11 @@ interface IProps {
         // Class applied to the element used to position the tooltip
         className: string,
         // Class applied to the tooltip itself
-        tooltipClassName: string,
+        tooltipClassName?: string,
         // Whether the tooltip is visible or hidden.
         // The hidden state allows animating the tooltip away via CSS.
         // Defaults to visible if unset.
-        visible: boolean,
+        visible?: boolean,
         // the react element to put into the tooltip
         label: React.ReactNode,
 }