WebGLRenderer: Use self instead of window.

[begmec]

Summary:
Three.js throws an exception when WebGLRenderer is disposed in a web-worker.

Reason:
On WebGLRenderer.dispose, WebGLAnimation.stop() is called. The "context" which is usually window, is not accessible in a
web-worker context.

Fix:
If context is not availabe, call request/cancelAnimationFrame without context

[Mugen87]

Instead of modifying WebGLAnimation, I wonder if could change the following line:

three.js/src/renderers/WebGLRenderer.js

Line 894 in aa01ab3

if ( typeof window !== 'undefined' ) animation.setContext( window );

to:

if ( typeof self !== 'undefined' ) animation.setContext( self ); 

[Mugen87]

self should work in the main thread and workers, see https://developer.mozilla.org/en-US/docs/Web/API/Window/self.

[begmec]

self should work in browsers and workers, see https://developer.mozilla.org/en-US/docs/Web/API/Window/self.

Thanks for the input! I changed window to self. It works in web-workers and in the main thread.

[mrdoob]

Thanks!