Visibility collapse
    Spec
    
    Setting a row to visibility:collapse changes table height but not width.
    Here, the spanning cell is the only cell in its row.
    
    
        
            B B B B B | 
        
        
            | aaaa | 
        
        
            | bbbb | 
        
        
            | cccc | 
        
        
            | dddd | 
        
    
    Bottom table is identical to top except second row has been collapsed.
    The spanning cell's height shrinks and is clipped.
    
        
            B B B B B | 
        
        
            | aaaa | 
        
        
            | bbbb | 
        
        
            | cccc | 
        
        
            | dddd | 
        
    
    This text should not intersect with the table.