This is shader linking freeze bug reproduction.
Reproducible in Chrome and Firefox on Windows 10 x64 with Nvidia hardware.

Steps:
1) Drop caches (especially in Chrome, as it seems to cache shader binaries)
2) Open console
3) Load this page.

Results:
Chrome should freeze for 10-20 seconds and print linking time approx 0.00001 seconds.
Firefox should freeze for 10-20 seconds and then print correct time.

Related bug reports:
ANGLE
Chromium
Firefox
No canvas