Backport PR matplotlib#32149: Always set device pixel ratio on WebSocket open in WebAgg

Author: ianthomas23

lib/matplotlib/backends/web_backend/js/mpl.js

@@ -64,11 +64,9 @@ mpl.figure = function (figure_id, websocket, ondownload, parent_element) {
     this.ws.onopen = function () {
         fig.send_message('supports_binary', { value: fig.supports_binary });
         fig.send_message('send_image_mode', {});
-        if (fig.ratio !== 1) {
-            fig.send_message('set_device_pixel_ratio', {
-                device_pixel_ratio: fig.ratio,
-            });
-        }
+        fig.send_message('set_device_pixel_ratio', {
+            device_pixel_ratio: fig.ratio,
+        });
         fig.send_message('refresh', {});
     };