[win32] Terminate app when main window closes
[win32] Terminate app when main window closes

We can't listen to window-all-closed any more since we have the shared
process window now.

shiftkey/desktop,artivilla/desktop,j-f1/forked-desktop,artivilla/desktop,gengjiawen/desktop,desktop/desktop,gengjiawen/desktop,BugTesterTest/desktops,BugTesterTest/desktops,shiftkey/desktop,say25/desktop,j-f1/forked-desktop,j-f1/forked-desktop,BugTesterTest/desktops,j-f1/forked-desktop,hjobrien/desktop,say25/desktop,kactus-io/kactus,artivilla/desktop,gengjiawen/desktop,hjobrien/desktop,BugTesterTest/desktops,desktop/desktop,say25/desktop,hjobrien/desktop,shiftkey/desktop,gengjiawen/desktop,desktop/desktop,kactus-io/kactus,artivilla/desktop,shiftkey/desktop,hjobrien/desktop,say25/desktop,kactus-io/kactus,kactus-io/kactus,desktop/desktop