Remove usage of private angular core API

[ThomasBurleson]

Current code uses imports and code such as:

import {ɵgetDOM as getDom} from '@angular/platform-browser';

return getDom().getStyle(element, styleName);

This is a private API. Replace this will solution similar to that used in @angular/material.

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}