Great news, the fix is coming in March 2018, see this link: https://developers.google.com/web/updates/2018/01/devtools
"Local Overrides let you make changes in DevTools, and keep those changes across page loads. Previously, any changes that you made in DevTools would be lost when you reloaded the page. Local Overrides work for most file types
How it works:
To set up Local Overrides:
UPDATE (March 19, 2018): It's live, detailed explanations here: https://developers.google.com/web/updates/2018/01/devtools#overrides