[PageControl] Fix bad indicator state when changing numberOfPages. (#1997)
[PageControl] Fix bad indicator state when changing numberOfPages. (#1997)

* [PageControl] Fix changing numberOfPages.

* [PageControl] address PR comments.

randallli/material-components-ios,sigito/material-components-ios,sigito/material-components-ios,material-components/material-components-ios,willlarche/material-components-ios,randallli/material-components-ios,material-components/material-components-ios,samnm/material-components-ios,samnm/material-components-ios,brianjmoore/material-components-ios,brianjmoore/material-components-ios,sigito/material-components-ios,material-components/material-components-ios,brianjmoore/material-components-ios,willlarche/material-components-ios,sigito/material-components-ios,samnm/material-components-ios,brianjmoore/material-components-ios,willlarche/material-components-ios,material-components/material-components-ios,material-components/material-components-ios,willlarche/material-components-ios,randallli/material-components-ios,randallli/material-components-ios,randallli/material-components-ios,brianjmoore/material-components-ios,samnm/material-components-ios,samnm/material-components-ios,sigito/material-components-ios,randallli/material-components-ios,willlarche/material-components-ios