Subject: [bug#35866]

From: Mike Rosset <[email-masked]>
Date: Wed, 29 May 2019 16:37:04 -0700

This patch ensures qtwebengine uses only Guix libraries. There are some
libraries that fail to be detect or are missing features. I have documented
them within the input expression.

Note. I'm not sure if I've sent this patch right. If this is wrong I can resend
the complete series