It's not always possible to push changes back to LESS or SASS due to ambiguity at which level changes should be applied - if you're editing CSS values. The browser would have to display SASS or LESS in the inspector for what you're suggesting to work.
Chrome Canary (perhaps, the Dev channel, too) supports navigation to CSS selectors, property names and values (Ctrl-click them) in the corresponding Sass resources (the Sources panel). You can edit Sass and save it to disk (right-click the editor, "Save as...").
Now, if you have the "Support for Sass" experiment enabled, you'll see the "Auto-reload CSS upon Sass save" timeout setting to reload re-generated CSS files after "sass --watch in:out --sourcemap" (or equivalent) has updated them on the local disk.