fix(material/stepper): icon not centered in header if direction changes (#24131)
fix(material/stepper): icon not centered in header if direction changes (#24131)

Fixes that the icon in the step header was being rendered outside of the circle of the page direction changes. This seems to be a browser rendering issue due to the fact that we were applying a `position: absolute` and a `transform` both on the icon and its parent. Since this is unnecessary, I've removed the styles from the icon and added an extra `display: flex` to fix the centering.

Fixes #24046.
crisbeto/material2,crisbeto/material2,angular/components,crisbeto/material2,angular/components,angular/components,crisbeto/material2,angular/components