Add webdriver command Find elements from element

components/script/script_thread.rs

@@ -1872,6 +1872,15 @@ impl ScriptThread {
                     reply,
                 )
             },
+            WebDriverScriptCommand::FindElementElementsCSS(selector,element_id,reply) => {
+                webdriver_handlers::handle_find_element_elements_css(
+                    &*documents,
+                    pipeline_id,
+                    element_id,
+                    selector,
+                    reply,
+                )
+            },
             WebDriverScriptCommand::FocusElement(element_id, reply) => {
                 webdriver_handlers::handle_focus_element(
                     &*documents,

components/script/webdriver_handlers.rs

@@ -220,6 +220,27 @@ pub fn handle_find_element_element_css(
     reply.send(node_id).unwrap();
 }
 
+pub fn handle_find_element_elements_css(
+    documents: &Documents,
+    pipeline: PipelineId,
+    element_id: String,
+    selector: String,
+    reply: IpcSender<Result<Option<String>, ()>>,
+){
+    let node_ids = find_node_by_unique_id(documents,pipeline,element_id)
+        .ok_or(())
+        .and_then(|node|{
+            node.query_selector_all(DOMString::from(selector)).map_err(|_| ())
+        })
+        .map(|nodes| {
+            nodes
+                .iter()
+                .map(|x| Some(x.upcast::<Node>().unique_id()))
+                .collect()
+        });
+    reply.send(node_ids).unwrap();
+}
+
 pub fn handle_focus_element(
     documents: &Documents,
     pipeline: PipelineId,