Chrome Version: 65.0.3325.181 (Official Build) (64-bit)
OS: Mac OS X

What steps will reproduce the problem?
(1) Navigate to https://en.wikipedia.org/wiki/1923_FA_Cup_Final
(2) Start mouse dragging in the first paragraph
(3) Without releasing, slowly move mouse down into the second paragraph

What is the expected result?

Selection doesn't flicker

What happens instead?

Selection flickers. When mouse moves to some position between the two paragraphs, the previous selection is unselected, and some text from the start of the first paragraph is selected instead.