Animation: Fix ReferenceError in non-broswer environment

Node.js and Deno do not support `self`.

Author: chirsz-ever

src/renderers/common/Animation.js

@@ -34,7 +34,10 @@ class Animation {
 		 *
 		 * @type {Window|XRSession}
 		 */
-		this._context = self;
+		this._context = typeof self !== 'undefined' ? self : // browser or Web Worker
+			typeof globalThis !== 'undefined' ? globalThis : // ES 2020
+			typeof global !== 'undefined' ? global : // Node.js
+			null;
 
 		/**
 		 * The user-defined animation loop.