title: File's properties: lastModified vs lastModifiedDate
body: <p><a href="https://developer.mozilla.org/en-US/docs/Web/API/File" rel="nofollow noreferrer">On the following page</a> they mention <code>lastModified</code> and <code>lastModifiedDate</code>. <code>lastModifiedDate</code> is working in every browser for me (FF, Chrome, IE, Edge, Opera) but it is written that is deprecated. <code>lastModified</code> doesn't exist in IE or Edge. So which to use?</p>