[gnome-builder/wip/gtk4-port] plugins/html-preview: fix use of hexpand/vexpand

[Christian Hergert <chergert src gnome org>]

commit 81abae2a1d6b17d014eeed12d7c17c99d09c9163
Author: Christian Hergert <chergert redhat com>
Date:   Wed Apr 20 16:53:50 2022 -0700

    plugins/html-preview: fix use of hexpand/vexpand

 src/plugins/html-preview/html_preview.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/plugins/html-preview/html_preview.py b/src/plugins/html-preview/html_preview.py
index 9a419eb34..1323d664e 100644
--- a/src/plugins/html-preview/html_preview.py
+++ b/src/plugins/html-preview/html_preview.py
@@ -362,7 +362,8 @@ class HtmlPreviewPage(Ide.Page):
         self.document = document
 
         self.webview = WebKit2.WebView()
-        self.webview.props.expand = True
+        self.webview.props.hexpand = True
+        self.webview.props.vexpand = True
         self.webview.connect('decide-policy', self.on_decide_policy_cb)
         self.add(self.webview)
         self.webview.show()