msxml3: Correct handling of listLength == NULL in IXMLDOMNamedNodeMap::get_length.

dlls/msxml3/nodemap.c

@@ -364,6 +364,9 @@ static HRESULT WINAPI xmlnodemap_get_length(
 
     TRACE("%p\n", This);
 
+    if( !listLength )
+        return E_INVALIDARG;
+
     node = xmlNodePtr_from_domnode( This->node, 0 );
     if ( !node )
         return E_FAIL;

dlls/msxml3/tests/domdoc.c

@@ -1003,6 +1003,9 @@ todo_wine
         SysFreeString( str );
 
 	/* test indexed access of attributes */
+        r = IXMLDOMNamedNodeMap_get_length( map, NULL );
+        ok ( r == E_INVALIDARG, "get_length should return E_INVALIDARG\n");
+
         r = IXMLDOMNamedNodeMap_get_length( map, &count );
         ok ( r == S_OK, "get_length wrong code\n");
         ok ( count == 1, "get_length != 1\n");