fix(ngrid): competability with cdk 8.1.3

Fixes #37

libs/ngrid/src/lib/table/features/virtual-scroll/virtual-scroll-viewport.component.html

@@ -12,7 +12,9 @@
   Spacer used to force the scrolling container to the correct size for the *total* number of items
   so that the scrollbar captures the size of the entire data set.
 -->
-<div class="cdk-virtual-scroll-spacer" [style.transform]="_totalContentSizeTransform"></div>
+<div class="cdk-virtual-scroll-spacer"
+     [style.width]="_totalContentWidth" [style.height]="_totalContentHeight"
+     [style.transform]="_totalContentSizeTransform"></div>
 <div *ngIf="pblFillerHeight"
     class="pbl-ngrid-space-fill"
     [style.minWidth.px]="minWidth"

libs/ngrid/src/lib/table/features/virtual-scroll/virtual-scroll-viewport.component.ts

@@ -149,6 +149,20 @@ export class PblCdkVirtualScrollViewportComponent extends CdkVirtualScrollViewpo
     return this.elementRef.nativeElement.getBoundingClientRect().width;
   }
 
+  /// TODO(shlomiassaf): Remove when not supporting 8.1.2 and below
+  /// COMPATIBILITY 8.1.2- <-> 8.1.3+
+    /** A string representing the `style.width` property value to be used for the spacer element. */
+    _totalContentWidth = '';
+    /** A string representing the `style.height` property value to be used for the spacer element. */
+   _totalContentHeight = '';
+    /**
+   * The transform used to scale the spacer to the same size as all content, including content that
+   * is not currently rendered.
+   * @deprecated
+   */
+  _totalContentSizeTransform = '';
+ /// COMPATIBILITY 8.1.2- <-> 8.1.3+
+
   private offsetChange$ = new Subject<number>();
   private offset: number;
   private isCDPending: boolean;