fix(Grid.js): ScrollIfNecessary does not account for scrollWidth correctly

Since scrollIfNecessary is called multiple times when enableCellEditOnFocus is true we need to make sure the scrollbarWidth and footerHeight is accounted for to not cause a loop.

fixes #6653

Author: macomage

Diff for: src/js/core/factories/Grid.js

@@ -2444,6 +2444,11 @@ angular.module('ui.grid')
           //   to get the full position we need
           scrollPixels = self.renderContainers.body.prevScrollTop - (topBound - pixelsToSeeRow);
 
+          //Since scrollIfNecessary is called multiple times when enableCellEditOnFocus is true we need to make sure the scrollbarWidth and footerHeight is accounted for to not cause a loop.
+          if (gridCol.colDef.enableCellEditOnFocus === true) {
+            scrollPixels = scrollPixels - self.footerHeight - self.scrollbarWidth;
+          }
+
           scrollEvent.y = getScrollY(scrollPixels, scrollLength, self.renderContainers.body.prevScrolltopPercentage);
         }
         // Otherwise if the scroll position we need to see the row is MORE than the bottom boundary, i.e. obscured below the bottom of the self...