Update setAccessor argument documentation. (#443)

src/dom/index.js

@@ -16,8 +16,9 @@ export function removeNode(node) {
  *	If `value` is `null`, the attribute/handler will be removed.
  *	@param {Element} node	An element to mutate
  *	@param {string} name	The name/key to set, such as an event or attribute name
- *	@param {any} value		An attribute value, such as a function to be used as an event handler
- *	@param {any} previousValue	The last value that was set for this name/node pair
+ *	@param {any} old	The last value that was set for this name/node pair
+ *	@param {any} value	An attribute value, such as a function to be used as an event handler
+ *	@param {Boolean} isSvg	Are we currently diffing inside an svg?
  *	@private
  */
 export function setAccessor(node, name, old, value, isSvg) {