timepicker navigation chevrons are not displayed properly

[pkozlowski-opensource]

Visit our demo page for timepicker with Safari on iOS: https://ng-bootstrap.github.io/#/components/timepicker

You will notice that navigation chevrons are not displayed properly due to the fact that we are using CSS to display those and iOS doesn't "understand" un-prefixed transform CSS properties: http://stackoverflow.com/questions/27303339/transform-not-working-on-ios

The simple fix is to add the -webkit-transform property as well. Fix to be done here:

ng-bootstrap/src/timepicker/timepicker.ts

Lines 29 to 36 in 20ad457

	transform: rotate(-45deg);
	vertical-align: middle;
	width: 0.71em;
	}
	.chevron.bottom:before {
	top: -.3em;
	transform: rotate(135deg);