Div having contentEditable and display:grid cannot be edited if it is empty.

Source/core/rendering/RenderFlexibleBox.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 643 matching lines @@
             ASSERT(inflexibleItems.size() > 0);
         }
 
         layoutAndPlaceChildren(crossAxisOffset, orderedChildren, childSizes, availableFreeSpace, relayoutChildren, lineContexts, hasInfiniteLineLength);
     }
     if (hasLineIfEmpty()) {
         // Even if computeNextFlexLine returns true, the flexbox might not have
         // a line because all our children might be out of flow positioned.
         // Instead of just checking if we have a line, make sure the flexbox
         // has at least a line's worth of height to cover this case.
-        LayoutUnit minHeight = borderAndPaddingLogicalHeight()
-            + lineHeight(true, isHorizontalWritingMode() ? HorizontalLine : VerticalLine, PositionOfInteriorLineBoxes)
-            + scrollbarLogicalHeight();
+        LayoutUnit minHeight = minimumLogicalHeightForEmptyLine();
         if (size().height() < minHeight)
             setLogicalHeight(minHeight);
     }
 
     updateLogicalHeight();
     repositionLogicalHeightDependentFlexItems(lineContexts);
 }
 
 LayoutUnit RenderFlexibleBox::autoMarginOffsetInMainAxis(const OrderedFlexItemList& children, LayoutUnit& availableFreeSpace)
 {
@@ skipping 724 matching lines @@
             ASSERT(child);
             LayoutUnit lineCrossAxisExtent = lineContexts[lineNumber].crossAxisExtent;
             LayoutUnit originalOffset = lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
             LayoutUnit newOffset = contentExtent - originalOffset - lineCrossAxisExtent;
             adjustAlignmentForChild(*child, newOffset - originalOffset);
         }
     }
 }
 
 }