fixup! fixup! test(material-experimental/mdc-slider): add two-way binding unit tests

Author: wagnermaciel

src/material-experimental/mdc-slider/slider.spec.ts

@@ -19,7 +19,7 @@ import {Thumb} from '@material/slider';
 import {MatSliderModule} from './module';
 import {MatSlider, MatSliderThumb, MatSliderVisualThumb} from './slider';
 
-type Point = {x: number; y: number};
+interface Point {x: number, y: number}
 
 describe('MDC-based MatSlider' , () => {
   let platform: Platform;