Enable use of Tools.LoadScript in a WebWorker (#12884)

* use importScripts instead of HTMLScriptElement when LoadScript is invoked in a WebWorker

* lint

Author: wmurphyrd

packages/dev/core/src/LibDeclarations/browser.d.ts

@@ -22,6 +22,12 @@ interface Window {
     setImmediate(handler: (...args: any[]) => void): number;
 }
 
+interface WorkerGlobalScope {
+    importScripts: (...args: string[]) => void;
+}
+
+type WorkerSelf = WindowOrWorkerGlobalScope & WorkerGlobalScope;
+
 interface HTMLCanvasElement {
     requestPointerLock(): void;
     msRequestPointerLock?(): void;

packages/dev/core/src/Misc/tools.ts

@@ -416,7 +416,16 @@ export class Tools {
      * @param scriptId defines the id of the script element
      */
     public static LoadScript(scriptUrl: string, onSuccess: () => void, onError?: (message?: string, exception?: any) => void, scriptId?: string) {
-        if (!IsWindowObjectExist()) {
+        if (typeof (self as unknown as WorkerSelf).importScripts === "function") {
+            try {
+                (self as unknown as WorkerSelf).importScripts(scriptUrl);
+                onSuccess();
+            } catch (e) {
+                onError?.(`Unable to load script '${scriptUrl}' in worker`, e);
+            }
+            return;
+        } else if (!IsWindowObjectExist()) {
+            onError?.(`Cannot load script '${scriptUrl}' outside of a window or a worker`);
             return;
         }
         const head = document.getElementsByTagName("head")[0];