Flashing background and flickering shape in webGL example

[mskwon]

The attached webGL example has unexpected background flashing and shape flickering when viewed with the Chromium browser obtained through the Raspbian repositories. The background flashing is from black to white, the pyramid on the left flickers.

I am using Raspbian. Kernel and packages are most recent as of 12/10/2016 via the Raspbian repositories and rpi-update.

webgl_example.zip