I attached a minimal example.

Deleted: evalSource_in_devtools.html 376 bytes

evalSource_in_devtools.html 376 bytes View Download

I run into the same issue while trying to investigate memory leaks in webpack. webpack dynamically compiles generated code (with `new Function`), which causes these leaks when devtools are attached.

I was able to reproduce this with

    (function test() {
        new Function();
        setImmediate(test);
    }());

I would propose that the devtools only hold a weak reference the functions.
That should not cause any issues since functions can't be called when not referenced. Maybe only hold a strong reference when breakpoints are set in the source or the source is open in the Sources panel.

In production this issue should not be critical, because devtools are rarely attached, but it makes investigating (real) memory leak much more difficult as much noise is generated by the devtools.

I attached an image of this leak in a real application.

Deleted: memory leak.PNG 176 KB

	memory leak.PNG 176 KB View Download

I have similar problems debugging a very huge application which is supposed to run 24/7: As long as the DevTools are open the used memory is rising very fast due to eval(). 
Maybe it would make sense to have a “Clear DevTools” button. Similar to the “Clear console” button.
Or have a cleanup after closing the DevTools (Snapshots are delete as well after closing).

Additionally, I’d like to link an other issue: https://bugs.chromium.org/p/chromium/issues/detail?id=870352 . Like suggested by kozy: the problems may be related and the right solution (e.g. if the object are not just filtered/hided or cleanup after closing) here could also help with the linked bug.

These both issues have the same root, DevTools store hard reference to all scripts to be able to request it content in future.