messageviewer does not wrap long JSONs with no spaces in email body, I have to use horizontal scrollbar while there's not good reason for that.

Reproducible: Always

Steps to Reproduce:
1. Receive a save to draft an email with smth like {"abacabadabacaba":"abacabadabacaba","totalVotePercentage":146,"favoriteBeer":"fdshfkljdshfkjncvjewrnfjewklewewfjkljewfkljewcklmwfjewkljewrfkewkljwkefj"}
2. Look at it in the message viewer in KMail.

Actual Results:  
The JSON makes the email width exceed the widget width, thus I have to use the scrollbar.

Expected Results:  
Wrap the line, at least after commas.

kmail 5.2.3


KDE Frameworks 5.24.0,
Qt 5.6.1 (собрана с версией 5.6.1),
Оконную систему xcb.