Revert Ico's nwjs-0.4x patchset.

Reverts the most recent changes from Ico's nwjs-0.4x patchset, excluding the changes from the unrelated remove-old-runners and dropdown-fixes branches which were also merged around June 21/22.

@ico, @jwilkes: This cleans up the master branch so that we can move Ico's nw.js 0.4x patchset to its own branch, and work can continue on the master branch while the 0.4x branch is still under review. I'll follow up with a second MR for that shortly.