Chrome Version       : 68 & 70
OS Version: OS X 10.13.6
URLs (if applicable): https://googlechromelabs.github.io/houdini-samples/paint-worklet/border-radius-reverse/


What steps will reproduce the problem?
1. Open https://googlechromelabs.github.io/houdini-samples/paint-worklet/border-radius-reverse/
2. Zoom in using Cmd+ 

What is the expected result?
Things get bigger

What happens instead of that?
Things get bigger and rounded corners disappear

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

UserAgentString: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36