fix(material/datepicker): wrong day of week read out for dates in first row (#23388)
fix(material/datepicker): wrong day of week read out for dates in first row (#23388)

The first row of cells has a cell with the month label which also has a `colspan` and `aria-hidden`. It looks like hiding the cell causes screen readers to ignore the cell competely and consider the cells after it to be first. This results in the wrong day of the week being read out for each date.
josephperrott/material2,angular/components,angular/components,crisbeto/material2,josephperrott/material2,crisbeto/material2,josephperrott/material2,angular/components,crisbeto/material2,josephperrott/material2,josephperrott/material2,angular/components,crisbeto/material2