Code review comment for lp://staging/~dandrader/unity8/miral

* See a bunch of inline comments

* I think we should not give up on the differntiation between claimFocus() and requestFocus(). One of them says the stage wants to actually focus something *now* while the other indicates that the app requested focus on its own (or perhaps u-a-l did). IMO claimFocus() should not be dropped and still do the raisId() call on the model. requestfocus() instead should end up in the shell, and if the shell is ok with doing so, it should call claimFocus() itself.

* IMO you're exaggerating with the debug messages. unity8.toplevelsurfacelist was already very annoying and this seems to have even more prints. Sure, you can argue that I could turn them off with the debug filter, which is what I do, but then I get none any more while the most important ones like raise() added() and removed() would still make sense.

This has been a code review for the code up until the mocks. Still needs review for tests/mocks and especially in depth testing.