Merge pull request microsoft#619 from Fabianopb/child-node

Override Node nextSibling to be type of ChildNode.

Author: sandersn

baselines/dom.generated.d.ts

@@ -10385,7 +10385,7 @@ interface Node extends EventTarget {
     /**
      * Returns the next sibling.
      */
-    readonly nextSibling: Node | null;
+    readonly nextSibling: ChildNode | null;
     /**
      * Returns a string appropriate for the type of node, as
      * follows:

inputfiles/overridingTypes.json

@@ -674,6 +674,9 @@
                             "read-only": 1,
                             "override-type": "string | null",
                             "deprecated": 1
+                        },
+                        "nextSibling": {
+                            "override-type": "ChildNode | null"
                         }
                     }
                 }