A <canvas> element used to render WebGL content does not render anything when flowed in a region.
Created attachment 203519 [details]
Works for me on today's nightly (r151543)
Created attachment 204682 [details]
The original test-case was for a different bug (that got fixed in the meanwhile)
Reopening as the bug still reproduces (tested with r151581)
Works now (after the accelerated compositing work). Closing as RESOLVED/INVALID.