[Maps] Fix cross origin error for icon spritesheets when Kibana secur…

…ed via OAuth proxy (#53896)

* Set crossOrigin to anonymous only on requests from external hosts

* Update x-pack/legacy/plugins/maps/public/connected_components/map/mb/utils.js

Co-Authored-By: Joe Portner <5295965+jportner@users.noreply.github.com>

* 🙇‍♂️ Lint

Co-authored-by: Joe Portner <5295965+jportner@users.noreply.github.com>
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

x-pack/legacy/plugins/maps/public/connected_components/map/mb/utils.js

@@ -110,7 +110,9 @@ function getImageData(img) {
 export async function loadSpriteSheetImageData(imgUrl) {
   return new Promise((resolve, reject) => {
     const image = new Image();
-    image.crossOrigin = 'Anonymous';
+    if (isCrossOriginUrl(imgUrl)) {
+      image.crossOrigin = 'Anonymous';
+    }
     image.onload = el => {
       const imgData = getImageData(el.currentTarget);
       resolve(imgData);
@@ -142,3 +144,13 @@ export async function addSpritesheetToMap(json, imgUrl, mbMap) {
   const imgData = await loadSpriteSheetImageData(imgUrl);
   addSpriteSheetToMapFromImageData(json, imgData, mbMap);
 }
+
+function isCrossOriginUrl(url) {
+  const a = window.document.createElement('a');
+  a.href = url;
+  return (
+    a.protocol !== window.document.location.protocol ||
+    a.host !== window.document.location.host ||
+    a.port !== window.document.location.port
+  );
+}