Fix transparency

[Mathias Bynens]

Try this transparent WebP image, for example: https://www.gstatic.com/webp/gallery3/1_webp_ll.webp

With WebPQuickLook, the preview looks like this instead:

[Emin Kura]

I fixed it, you can update by removing ~/Library/QuickLook/WebpQuickLook.qlgenerator folder and repeating the steps which I wrote for installation. Thanks for addressing the problem.
Btw, It's kinda embarrassing for me that I never tested transparent images :)

[Mathias Bynens]

Thanks for the quick fix!