Bug 221288 XUL tree builder abuses tree batching r=jan sr=alecf

content/xul/templates/src/nsXULTreeBuilder.cpp

@@ -1350,13 +1350,15 @@ nsXULTreeBuilder::RebuildAll()
     if (!doc)
         return NS_OK;
 
-    if (mBoxObject) {
-        mBoxObject->BeginUpdateBatch();
-    }
-
+    PRInt32 count = mRows.Count();
     mRows.Clear();
     mConflictSet.Clear();
 
+    if (mBoxObject) {
+        mBoxObject->BeginUpdateBatch();
+        mBoxObject->RowCountChanged(0, -count);
+    }
+
     nsresult rv = CompileRules();
     if (NS_FAILED(rv)) return rv;