Created attachment 130867 [details]
Random blinking spots instead of squares

When viewing <https://robertsspaceindustries.com/starmap> you can see random
blinking patches (see attached screenshot) instead of full screen of blinking
squares in the background during the loading screens. The first few seconds of
<https://www.youtube.com/watch?v=Xn3MeDnryt8> show how the background should
look.
Please note, that the actual star map works fine AFAICT (thus the reduced
severity and priority).
This is with the OpenGL stack detailed below and Firefox 52.0.2. Also this
doesn't seem to be a duplicate of bug 100036 as that star map seems to render
correctly for me with the same setup.

The full stack (Debian testing as a base) is:
GPU: Hawaii PRO [Radeon R9 290] (ChipID = 0x67b1)
Mesa: Git:master/566f2ed571
libdrm: Git:master/c9c77c3717 (tag libdrm-2.4.79)
LLVM: SVN:trunk/r299977 (5.0 devel)
X.Org: 2:1.19.2-1
Linux: 4.10.9
Firmware (firmware-amd-graphics): 20161130-2
libclc: 0.2.0+git20170330-1 (rebuilt for LLVM 5.0)
DDX (xserver-xorg-video-amdgpu): 1.2.0-1+b1

Let me know if you need anything else.