test(material-experimental/mdc-slider): try to reduce test flakes

We've been seeing more test flakes from the MDC slider recently. These changes try to address them by disabling animations and adding an extra change detection after flushing `requestAnimationFrame`.

Author: crisbeto

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

@@ -24,12 +24,19 @@ import {Component, DebugElement, Type, ViewChild} from '@angular/core';
 import {ComponentFixture, fakeAsync, flush, TestBed, tick, inject} from '@angular/core/testing';
 import {FormControl, FormsModule, ReactiveFormsModule} from '@angular/forms';
 import {By} from '@angular/platform-browser';
+import {NoopAnimationsModule} from '@angular/platform-browser/animations';
 import {MatSlider, MatSliderModule} from './index';
 
 describe('MDC-based MatSlider', () => {
   function createComponent<T>(component: Type<T>): ComponentFixture<T> {
     TestBed.configureTestingModule({
-      imports: [MatSliderModule, ReactiveFormsModule, FormsModule, BidiModule],
+      imports: [
+        MatSliderModule,
+        ReactiveFormsModule,
+        FormsModule,
+        BidiModule,
+        NoopAnimationsModule,
+      ],
       declarations: [component],
     }).compileComponents();