HTML5 Canvas restarts the browser on an RPi3

[fhunleth]

Creating the canvas is fine, but once you draw something to it, Chromium crashes and dumps a stack trace. This only appears to happen on Raspberry Pi 3's.

Here's a link to the upstream Qt bug:

https://bugreports.qt.io/browse/QTBUG-67323?page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel&showAll=true

The current workaround is to disable hardware acceleration. Before you start the webengine kiosk, run this:

System.put_env("QTWEBENGINE_CHROMIUM_FLAGS", "--disable-gpu")