Collecting coverage stats from a child frame or window

Is there any way to do this? I'm trying to write tests for a module which has components across multiple parent windows and iframes, and obviously right now the only coverage stats which are collected is for code running in the top level window.

Start by examining how karma-coverage collects coverage from the top-level window and compare that with the issue's child-frame and child-window test setup. Determine whether coverage can be collected across those contexts and define the expected result for code running outside the top-level window.

Written by the indexing model from the issue text.