Revert "Optimize CalendarHeader to not rerender if current month wasn't changed"
Revert "Optimize CalendarHeader to not rerender if current month wasn't changed"

This reverts commit beec554c31f81785502c5bf5866896b6b86c8a0f.

callemall/material-ui,callemall/material-ui,callemall/material-ui,rscnt/material-ui,mbrookes/material-ui,rscnt/material-ui,dmtrKovalenko/material-ui-pickers,rscnt/material-ui,callemall/material-ui,oliviertassinari/material-ui,oliviertassinari/material-ui,dmtrKovalenko/material-ui-pickers,mbrookes/material-ui,mbrookes/material-ui,mui-org/material-ui,mui-org/material-ui,oliviertassinari/material-ui,mui-org/material-ui