Make Document.body non-nullable

Author: mhegazy

baselines/dom.generated.d.ts

@@ -3930,7 +3930,7 @@ interface Document extends Node, NonElementParentNode, DocumentOrShadowRoot, Par
     /**
      * Specifies the beginning and end of the document body.
      */
-    body: HTMLElement | null;
+    body: HTMLElement;
     /**
      * Returns document's encoding.
      */

inputfiles/overridingTypes.json

@@ -477,7 +477,10 @@
                         },
                         "location": {
                             "read-only": 0
-                        }
+                        },
+                        "body": {
+                            "nullable": false
+                       }
                     }
                 }
             },