BLASTSyncEngine: Skip invisible windows

They will never report drawing so they could stall
our sync until the timeout happens. We have this logic
in the WindowContainer implementation bug forgot it in
the WindowState.

Bug: 148871522
Bug: 139371701
Test: TaskOrganizerTests#testBLASTCallbackWithInvisibleWindow
Change-Id: Ibf6f720f91f1d832ea049bea8b47041e038eae5e