push should return a ThenableReference

Author: Feiyang1

packages/database-types/index.d.ts

@@ -108,7 +108,7 @@ export interface Reference extends Query {
   key: string | null;
   onDisconnect(): OnDisconnect;
   parent: Reference | null;
-  push(value?: any, onComplete?: (a: Error | null) => any): Reference;
+  push(value?: any, onComplete?: (a: Error | null) => any): ThenableReference;
   remove(onComplete?: (a: Error | null) => any): Promise<any>;
   root: Reference;
   set(value: any, onComplete?: (a: Error | null) => any): Promise<any>;