Delete redundancy ( Performance: Cut rendering time in half for the sample index.html )

[edom18]

I have found redundancy codes. I have deleted it.

[edom18]

I have noticed an issue in Nightly. The first commit of my PR that deleted twice calling rendering method. So twice calling is very heavy for Nightly. After deleting it, Nightly is very fast running in VR mode.

[haeric]

👍 to this PR. The description is sparse, but the change is important. The title of this PR could better be explained Performance: Cut rendering time in half.

effect.render(scene, camera); effectively renders the VREffect a second time, after the manager has already done it. This means that everyone using this boilerplate is effectively seeing double the rendering time, which originally made me seriously question the performance of WebVR on the Google Pixel.

One could also go the opposite route, and remove/deprecate the .render() from the WebVRManager. But it's more hassle to change the WebVRManager constructor, assuming we want to deprecate and not just flat out remove.

This change was tested on Pixel and Pixel XL:
Chrome Beta 56.0.2924.53
Chrome Dev 57.0.2977.0

[edom18]

Thank you for comment. I've rewrite the subject of PR :)