Load images the panel redirects to the app's server with CORS

The app treats those images as its own site's and loads them without
CORS, so once they come from the app's server WebGL refuses them and
Cesium stops rendering.

src/tools/globePanel.js

@@ -149,7 +149,12 @@ function panelHtml(appOrigin) {
       Object.defineProperty(type.prototype, attribute, {
         ...property,
         set(value) {
-          property.set.call(this, toApp(value));
+          const target = toApp(value);
+          // The app treated the address as its own site; now that it is
+          // another site, images must load with CORS or WebGL refuses them.
+          if (target !== value && 'crossOrigin' in this && this.crossOrigin === null)
+            this.crossOrigin = 'anonymous';
+          property.set.call(this, target);
         },
       });
     }
@@ -184,8 +189,10 @@ function panelHtml(appOrigin) {
           if (node.nodeType !== 1) continue;
           for (const element of [node, ...node.querySelectorAll('[src]')]) {
             const value = element.getAttribute('src');
-            if (value && toApp(value) !== value)
-              element.setAttribute('src', toApp(value));
+            if (!value || toApp(value) === value) continue;
+            if ('crossOrigin' in element && element.crossOrigin === null)
+              element.crossOrigin = 'anonymous';
+            element.setAttribute('src', toApp(value));
           }
         }
       }