fix(igxFor): Resetting scroll position cache in case scrollbar size i… (#5351)

* fix(igxFor): Resetting scroll position cache in case scrollbar size is changes so that it no longer shows scrollbar.

* chore(*): Fixing whitespaces.

* chore(*): Additional fix in case container size is string.

Author: MayaKirova

projects/igniteui-angular/src/lib/directives/for-of/for_of.directive.ts

@@ -1086,19 +1086,21 @@ export class IgxForOfDirective<T> implements OnInit, OnChanges, DoCheck, OnDestr
 
     protected _recalcScrollBarSize() {
         const count = this.isRemote ? this.totalItemCount : (this.igxForOf ? this.igxForOf.length : 0);
-        const prevNotVirtual = this.dc.instance.notVirtual;
         this.dc.instance.notVirtual = !(this.igxForContainerSize && this.dc && this.state.chunkSize < count);
-        if (!prevNotVirtual && prevNotVirtual !== this.dc.instance.notVirtual) {
-            this._scrollPosition = 0;
-        }
         if (this.igxForScrollOrientation === 'horizontal') {
             const totalWidth = this.igxForContainerSize ? this.initSizesCache(this.igxForOf) : 0;
             this.hScroll.style.width = this.igxForContainerSize + 'px';
             this.hScroll.children[0].style.width = totalWidth + 'px';
+            if (totalWidth <= parseInt(this.igxForContainerSize, 10)) {
+                this.scrollPosition = 0;
+            }
         }
         if (this.igxForScrollOrientation === 'vertical') {
             this.vh.instance.elementRef.nativeElement.style.height = parseInt(this.igxForContainerSize, 10) + 'px';
             this.vh.instance.height = this._calcHeight();
+            if (this.vh.instance.height <= parseInt(this.igxForContainerSize, 10)) {
+                this.scrollPosition = 0;
+            }
         }
     }
 
@@ -1126,7 +1128,7 @@ export class IgxForOfDirective<T> implements OnInit, OnChanges, DoCheck, OnDestr
         if (prevChunkSize !== this.state.chunkSize) {
             this.onChunkLoad.emit(this.state);
         }
-        if (this.sizesCache && this.hScroll && this.scrollPosition !== 0) {
+        if (this.sizesCache && this.hScroll) {
             // Updating horizontal chunks and offsets based on the new scrollLeft
             const scrollOffset = this.fixedUpdateAllElements(this.scrollPosition);
             this.dc.instance._viewContainer.element.nativeElement.style.left = -scrollOffset + 'px';