MFH: r476599

www/chromium: Update to 68.0.3440.84

Changelog: https://chromium.googlesource.com/chromium/src/+log/67.0.3396.87..68.0.3440.84?pretty=fuller&n=10000

At the moment pkg-message says that in order to work around the hanging tabs problem the user may wish to run the following commands:

1. [ -d ~{user}/.cache/chromium ] || mkdir ~{user}/.cache/chromium
2. echo "md $(echo ~{user})/.cache/chromium mfs rw,late,-w{user}:{group},-s300m 2 0" >> /etc/fstab
3. mount ~{user}/.cache/chromium

Add fix-hanging-tabs.sh script to the DATADIR [1], which simplifies the process to just running

/usr/local/share/chromium/fix-hanging-tabs.sh $user $group

PR: 230264 [1]
Submitted by: 0mp [1]
Security: http://vuxml.freebsd.org/freebsd/b9c525d9-9198-11e8-beba-080027ef1a23.html

Approved by: ports-secteam (miwi)