UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0

Example URL:
https://codepen.io/anon/pen/oEzNRQ

Steps to reproduce the problem:
1. Open Chrome on Windows on a HiDPI screen (tested on 200% scale)
2. Alternatively, open Chrome on normal DPI screen with "--force-device-scale-factor=2" command line option
3. Open https://codepen.io/anon/pen/oEzNRQ
4. Click on "Draw Images" button
2. Click 
3. 

What is the expected behavior?
Image is drawn repeatedly on canvas without any artifact. Image is the letter "b" with a black bar on the right. The black bar should be overwritten by the next drawn image.

What went wrong?
1-pixel wide vertical artifacts appear between drawn images.

This also occurs if images overlap vertically (1-pixel high horizontal artifact in that case).

Does it occur on multiple sites: Yes

Is it a problem with a plugin? No 

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: Version 66.0.3341.0 (Official Build) canary (64-bit)  Channel: canary
OS Version: 10.0
Flash Version: 

From time to time, if a cursor is passed over the images or if other page areas are selected, the canvas refreshes and the artifacts disappear.

These artifacts do not appear on a regular screen which is not scaled.

Also, this behaviour does not occur in other browsers (tested with Microsoft Edge and Firefox). It doesn't appear to occur on other operating systems (Chrome on Linux and Chrome on OS X), although further testing should be performed.