Fixup File API

dom/src/main/scala/org/scalajs/dom/File.scala

@@ -19,8 +19,28 @@ import scala.scalajs.js.annotation._
  */
 @js.native
 @JSGlobal
-abstract class File extends Blob {
+abstract class File[A](bits: js.Iterable[A], name: String, options: FileOptions) extends Blob {
 
  /** Returns the name of the file. For security reasons, the path is excluded from this property. */
  def name: String = js.native
+
+ /** The File.lastModified read-only property provides the last modified date of the file as the number of milliseconds
+ * since the Unix epoch (January 1, 1970 at midnight). Files without a known last modified date return the current
+ * date.
+ */
+ def lastModified: Int = js.native
+
+ /** The File.webkitRelativePath is a read-only property that contains a string which specifies the file's path
+ * relative to the directory selected by the user in an <input> element with its webkitdirectory attribute set.
+ *
+ * @return
+ * A string containing the path of the file relative to the ancestor directory the user selected.
+ */
+ def webkitRelativePath: String = js.native
+}
+
+/** An options object containing optional attributes for the file. */
+trait FileOptions extends js.Object {
+ var `type`: js.UndefOr[String] = js.undefined
+ var lastModified: js.UndefOr[Int] = js.undefined
 }