fix: allow scriptlets being used as resources

refs https://github.com/gorhill/uBlock/wiki/Resources-Library
refs ghostery#4392
fixes ghostery#4393

packages/adblocker/src/resources.ts

@@ -298,7 +298,10 @@ export default class Resources {
   }
 
   public getResource(name: string): { body: string; contentType: string; dataUrl: string } {
-    const { body, contentType } = this.resourcesByName.get(name) || getResourceForMime(name);
+    const { body, contentType } =
+      this.resourcesByName.get(name) ||
+      this.getScriptletAsResource(name) ||
+      getResourceForMime(name);
 
     let dataUrl;
     if (contentType.indexOf(';') !== -1) {
@@ -346,6 +349,23 @@ export default class Resources {
     return this.scriptletsByName.get(name.endsWith('.js') ? name : `${name}.js`);
   }
 
+  private getScriptletAsResource(name: string): { body: string; contentType: string } | undefined {
+    // Do not skip `.js` when the scriptlet is used with `redirect=`, only when used in `+js(...)`.
+    if (name.endsWith('.js') === false) {
+      return undefined;
+    }
+
+    const scriptlet = this.scriptletsByName.get(name);
+    if (scriptlet === undefined) {
+      return undefined;
+    }
+
+    return {
+      body: scriptlet.body,
+      contentType: 'application/javascript',
+    };
+  }
+
   private getScriptletDependencies(scriptlet: Scriptlet): string[] {
     const dependencies: Map<string, string> = new Map();
     const queue: string[] = [...scriptlet.dependencies];