webdriver: Raise WebView to top when focus (#38909)

- Add a helper function `focus_and_raise_to_top` to `WebView`.
- For webdriver, raise webview to top when focus, to make it consistent
with user interaction.

Testing: Should reduce some flaky TIMEOUT when combined with another PR
later.
Fixes: A small patch before the PR for #38906.

---------

Signed-off-by: Euclid Ye <euclid.ye@huawei.com>

ports/servoshell/desktop/app.rs

@@ -376,7 +376,7 @@ impl App {
                 },
                 WebDriverCommandMsg::FocusWebView(webview_id, response_sender) => {
                     if let Some(webview) = running_state.webview_by_id(webview_id) {
-                        let focus_id = webview.focus();
+                        let focus_id = webview.focus_and_raise_to_top(true);
                         running_state.set_pending_focus(focus_id, response_sender);
                     }
                 },

ports/servoshell/desktop/app_state.rs

@@ -120,8 +120,7 @@ impl RunningAppState {
 
     pub(crate) fn create_and_focus_toplevel_webview(self: &Rc<Self>, url: Url) {
         let webview = self.create_toplevel_webview(url);
-        webview.focus();
-        webview.raise_to_top(true);
+        webview.focus_and_raise_to_top(true);
     }
 
     pub(crate) fn create_toplevel_webview(self: &Rc<Self>, url: Url) -> WebView {
@@ -634,8 +633,7 @@ impl WebViewDelegate for RunningAppState {
         // as that is what the specification expects. Otherwise, we would like `window.open()`
         // to create a new foreground tab
         if self.servoshell_preferences.webdriver_port.is_none() {
-            webview.focus();
-            webview.raise_to_top(true);
+            webview.focus_and_raise_to_top(true);
         }
         self.add(webview.clone());
         Some(webview)

ports/servoshell/desktop/headed_window.rs

@@ -406,12 +406,8 @@ impl Window {
             })
             .shortcut(Modifiers::CONTROL, Key::Named(NamedKey::PageUp), || {
                 if let Some(index) = state.get_focused_webview_index() {
-                    let new_index = if index == 0 {
-                        state.webviews().len() - 1
-                    } else {
-                        index - 1
-                    };
-                    state.focus_webview_by_index(new_index)
+                    let len = state.webviews().len();
+                    state.focus_webview_by_index((index + len - 1) % len);
                 }
             })
             .shortcut(CMD_OR_CONTROL, 'T', || {