Update Map.clear and Set.clear jsdoc in es2015.collection.d.ts

Author: btoo

src/lib/es2015.collection.d.ts

@@ -1,4 +1,7 @@
 interface Map<K, V> {
+    /**
+     * Removes all elements from this map
+     */
     clear(): void;
     /**
      * @returns true if an element in the Map existed and has been removed, or false if the element does not exist.
@@ -73,7 +76,9 @@ interface Set<T> {
      * Appends a new element with a specified value to the end of the Set.
      */
     add(value: T): this;
-
+    /**
+     * Removes all elements from this set
+     */
     clear(): void;
     /**
      * Removes a specified value from the Set.