Fix shader setter not updating hasShaderUpdater and hasShaderTimeFn

[guilhermesimoes]

Fix crash:

TypeError: this.shader.update is not a function

caused by doing:

this.bar = renderer.createNode({
    w: BAR_WIDTH,
    h: BAR_HEIGHT,
    color: 0x00000000,
    shader: renderer.createShader('border', { w: 4, color: 0x000000cc }),
});

setTimeout(() => {
  this.bar.shader = renderer.createShader('default');
}, 5000);

Now, the properties hasShaderUpdater and hasShaderTimeFn are always updated when the shader is set to null or to the default shader.

[jfboeve]

Nice find!