fix(slider): apply additional fixes related to IE11

Closes #3449

Author: Aleksandyr

projects/igniteui-angular/src/lib/slider/slider.component.html

@@ -3,7 +3,7 @@
     class="igx-slider"
     [class.igx-slider--disabled]="disabled"
     (pointerdown)="findClosestThumb($event)"
-    (pan)="update($event.srcEvent.x)"
+    (pan)="update($event.srcEvent.clientX)"
     (tap)="onTap($event)">
     <div class="igx-slider__track">
         <div #track class="igx-slider__track-fill"></div>

projects/igniteui-angular/src/lib/slider/slider.component.ts

@@ -858,7 +858,7 @@ export class IgxSliderComponent implements
      * @hidden
      */
     public onTap($event) {
-        this.update($event.srcEvent.x);
+        this.update($event.srcEvent.clientX);
     }
     /**
      *