chore(*): Attempt to fix mch tests.

Author: MKirova

projects/igniteui-angular/src/lib/grids/grid/column-group.spec.ts

@@ -303,7 +303,8 @@ describe('IgxGrid - multi-column headers #grid', () => {
         grid.ngAfterViewInit();
 
 
-        const availableWidth = (parseInt(componentInstance.gridWrapperWidthPx, 10) - grid.scrollWidth).toString();
+        const scrWitdh = grid.nativeElement.querySelector('.igx-grid__tbody-scrollbar').getBoundingClientRect().width;
+        const availableWidth = (parseInt(componentInstance.gridWrapperWidthPx, 10) - scrWitdh).toString();
         const locationColGroup = getColGroup(grid, 'Location');
         const colWidth = Math.round(parseInt(availableWidth, 10) / 3);
         const colWidthPx = colWidth + 'px';
@@ -326,7 +327,8 @@ describe('IgxGrid - multi-column headers #grid', () => {
         grid.width = gridWidth;
         tick();
         fixture.detectChanges();
-        const gridWidthInPx = parseInt(gridWidth, 10) - grid.scrollWidth;
+        const scrWitdh = grid.nativeElement.querySelector('.igx-grid__tbody-scrollbar').getBoundingClientRect().width;
+        const gridWidthInPx = parseInt(gridWidth, 10) - scrWitdh;
         const colWidth = Math.round(gridWidthInPx / 3);
         const colWidthPx = colWidth + 'px';
         const locationColGroup = getColGroup(grid, 'Location');
@@ -350,8 +352,10 @@ describe('IgxGrid - multi-column headers #grid', () => {
         tick();
         fixture.detectChanges();
 
+        const scrWitdh = grid.nativeElement.querySelector('.igx-grid__tbody-scrollbar').getBoundingClientRect().width;
+
         const gridWidthInPx = (parseInt(gridWidth, 10) / 100) *
-            parseInt(componentInstance.gridWrapperWidthPx, 10) - grid.scrollWidth;
+            parseInt(componentInstance.gridWrapperWidthPx, 10) - scrWitdh;
         const colWidth = Math.round(gridWidthInPx / 3);
         const colWidthPx = colWidth + 'px';
         const locationColGroup = getColGroup(grid, 'Location');