Ditch WebVR polyfill do barrel distortion in vertex shader.

[AdaRoseCannon]

• WebVR provides mouse/touch interaction for dragging the camera.
• As well as the head tracking using device orientation apis.
• Barrel distortion is performed by buffering the whole scene into a new texture and rendering it on a distorted plane.

A better solution would be to perform this distortion using a Vertex Shader for increased resolution and performance.