Fix XML loading in wasm demo app. Fixes #2960

PiperOrigin-RevId: 853635752
Change-Id: I20226de32f3141d40ec56956451f91ec7299e727

wasm/demo_app/app.ts

@@ -208,7 +208,7 @@ class App {
     // Write xml as a file so that mujoco can find it
     (mujoco as any).FS.writeFile('/working/model.xml', xmlContent);
 
-    this.mjModel = mujoco.MjModel.loadFromXML('/working/model.xml');
+    this.mjModel = mujoco.MjModel.mj_loadXML('/working/model.xml');
     if (!app.mjModel) {
       throw new Error('Failed to load model');
     }