gnome-shell 40: Use unique unlock-dialog style class

src/gnome-shell/sass/components/gdm/_login-dialog.scss

@@ -5,7 +5,8 @@

                                
                                
                                
                            
                                
                                    
                                        
                                            5  
                                              max-width: 23em;
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            6  
                                            }
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            7  
                                            
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        8 -
                                        .login-dialog {
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        8 +
                                        .login-dialog,
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        9 +
                                        .unlock-dialog {
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            10  
                                              //reset
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            11  
                                              border: 0;
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            12  
                                              background-color: transparent;