Bug
1878037 - Fix some regressions on alert windows. r=saschanaz,win-reviewers,rkraesig
Bug
1870512 removed top level windows with WindowType::Popup, instead
replacing it with an "alert" feature for the only use of them that we
had.
Turns out that on Windows they need a bit more special handling than I
thought, so this patch uses the alert boolean to fix two regressions
(that alerts now create taskbar icons, and that they steal focus).
Remove mIsForMenuPopupFrame since that is now a synonym with
WindowType::Popup.
Remove also the dialog vs. toplevel difference of using
WS_EX_DLGMODALFRAME, since that doesn't seem to have an effect at all on
windows 10+.
Differential Revision: https://phabricator.services.mozilla.com/
D200508