Fix DataSnapshot size

Author: shepeliev

firebase-common/src/jsMain/kotlin/dev/gitlive/firebase/externals/database/database.kt

@@ -115,10 +115,10 @@ external interface ThenableReference : DatabaseReference
 
 external interface DataSnapshot {
     val key: String?
+    val size: Int
     fun `val`(): Any
     fun exists(): Boolean
     fun forEach(action: (a: DataSnapshot) -> Boolean): Boolean
-    fun numChildren(): Int
     fun child(path: String): DataSnapshot
 }
 

firebase-database/src/jsMain/kotlin/dev/gitlive/firebase/database/database.kt

@@ -164,7 +164,7 @@ actual class DataSnapshot internal constructor(val js: JsDataSnapshot) {
     actual fun child(path: String) = DataSnapshot(js.child(path))
 
     actual val children: Iterable<DataSnapshot> = rethrow {
-        ArrayList<DataSnapshot>(js.numChildren()).also {
+        ArrayList<DataSnapshot>(js.size).also {
             js.forEach { snapshot -> it.add(DataSnapshot(snapshot)) }
         }
     }