Chrome Version       : 61.0.3163.38
OS Version: 9765.21.0

What steps will reproduce the problem?
0. view this bug report
1. double click "word" in this sentence so it's highlighted
2. while holding the click, move the mouse down to select the following lines
3. while still holding, move the mouse up to select the previous lines
4. while still holding, move the mouse back down to following lines
5. observe that the previously double clicked/selected "word" is now dropped from the selection, and the selection start has moved from the start of the word to the end of the word

What is the expected result?
"word" should have stayed selected in its entirety at all times

What happens instead of that?
"word" is dropped from the selection

UserAgentString: Mozilla/5.0 (X11; CrOS x86_64 9765.21.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.38 Safari/537.36

this is a regression, but i don't recall when exactly i noticed it.  figured i'd wait a bit to see if someone else would find/fix it.  that has not happened ;).

behavior seems to be CrOS specific.  at least, macOS & Linux don't exhibit this issue with R60/R62.