Chrome Version       : 63.0.3239.132 (Official Build) (64-bit)
URLs (if applicable) :gmail.com
Other browsers tested: None


What steps will reproduce the problem?
(1) Send a message with two paragraphs of indented text.
(2) Look at that message in 'sent', copy the paragraphs
(3) Paste to a new message via 'Compose'
(4) Select them and click on the 'un-indent' format button

What is the expected result?

Movement to the left.


What happens instead?

Page hangs, eventually pops up 'shall I kill this page' dialog.


Please provide any additional information below. Attach a screenshot if
possible.