Add new and correct existing fns in DataTransfer

Author: japgolly

src/main/scala/org/scalajs/dom/raw/lib.scala

@@ -3759,6 +3759,15 @@ trait DataTransfer extends js.Object {
  * MDN
  */
  var dropEffect: String = js.native
+
+ /**
+ * Set the drag source. Usually you would not change this, but it will affect which node
+ * the drag and dragend events are fired at. The default target is the node that was dragged.
+ *
+ * MDN
+ */
+ def addElement(element: Element): Unit = js.native
+
  /**
  * Remove the data associated with a given type. The type argument is optional. If the
  * type is empty or not specified, the data associated with all types is removed. If
@@ -3767,7 +3776,7 @@ trait DataTransfer extends js.Object {
  *
  * MDN
  */
- def clearData(format: String = js.native): Boolean = js.native
+ def clearData(`type`: String = js.native): Unit = js.native
 
  /**
  * Set the data for a given type. If data for the type does not exist, it is added at the
@@ -3777,15 +3786,37 @@ trait DataTransfer extends js.Object {
  *
  * MDN
  */
- def setData(format: String, data: String): Boolean = js.native
+ def setData(`type`: String, data: String): Unit = js.native
+
+ /**
+ * Set the image to be used for dragging if a custom one is desired. Most of the time, this
+ * would not be set, as a default image is created from the node that was dragged.
+ *
+ * If the node is an HTML img element, an HTML canvas element or a XUL image element, the
+ * image data is used. Otherwise, image should be a visible node and the drag image will be
+ * created from this. If image is null, any custom drag image is cleared and the default is
+ * used instead.
+ *
+ * The coordinates specify the offset into the image where the mouse cursor should be. To
+ * center the image, for instance, use values that are half the width and height of the image.
+ *
+ * @param image An element to use as the drag feedback image.
+ * @param x Horizontal offset within the image.
+ * @param y Vertical offset within the image.
+ */
+ def setDragImage(image: Element, x: Double, y: Double): Unit = js.native
 
  /**
  * Retrieves the data for a given type, or an empty string if data for that type does not
  * exist or the data transfer contains no data.
  *
+ * A security error will occur if you attempt to retrieve data during a drag that was set
+ * from a different domain, or the caller would otherwise not have access to. This data will
+ * only be available once a drop occurs during the drop event.
+ *
  * MDN
  */
- def getData(format: String): String = js.native
+ def getData(`type`: String): String = js.native
 
  /**
  * Holds a list of the format types of the data that is stored for the first item, in the