Deleting messages in a large chat w/ a timer seems to cause a memory leak

[Dyras]

• I have searched open and closed issues for duplicates

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Bug description

A friend of mine asked me to clean her conversation with me, so I tried to delete all the messages in our chat. It proceeds to load for aaaaaaaaaaaaaages and according to task manager, Chrome now uses over 1 gigabyte of RAM.

Steps to reproduce

1. Enable expiring messages in the chat
2. Chat a lot with this person
3. Try to delete the contents of the chat
4. Wait for your brain to freeze
5. Eventually Signal will start to function like normal, but it will have a bizarre amount of memory used
6. The messages are gone, but the files on the computer are still there
   https://vgy.me/UfDNuP.png

Actual result: Chrome loads for ages, and never deletes the actual messages
Expected result: The messages should delete without Signal getting stuck for ages

Screenshots

https://vgy.me/kZtvfI.png Task Manager shows over 1 gigabyte of RAM being used

Platform info

Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36 Signal-Desktop/0.29.0

Link to debug log

https://gist.github.com/6ccd9cbc63072c645fa94646b1c33f28
Doesn't seem to show anything too exciting though.

Possibly related

#962