Allow Grid.props.isScrolling to override Grid.state.isScrolling in _c…

…alculateChildrenToRender

source/Grid/Grid.js

@@ -120,6 +120,11 @@ export default class Grid extends PureComponent {
      */
     id: PropTypes.string,
 
+    /**
+     * Provide a way to override isScrolling through props. Useful for WindowScroller to use cell caching.
+     */
+    isScrolling: PropTypes.bool,
+
     /**
      * Optional renderer to be used in place of rows when either :rowCount or :columnCount is 0.
      */
@@ -751,13 +756,18 @@ export default class Grid extends PureComponent {
     } = props
 
     const {
-      isScrolling,
       scrollDirectionHorizontal,
       scrollDirectionVertical,
       scrollLeft,
       scrollTop
     } = state
 
+    let isScrolling = state.isScrolling;
+    if (Object.hasOwnProperty.call(props, 'isScrolling')) {
+      // If isScrolling is defined in props, use it to override the value in state
+      isScrolling = props.isScrolling
+    }
+
     this._childrenToDisplay = []
 
     // Render only enough columns and rows to cover the visible area of the grid.