anchor.diff:        child = child.parentData.nextSibling;
       }
   
  -    // Section 8.2: Axis Alignment using the justify-content property
  +    // Section 8.2: Main Axis Alignment using the justify-content property
       double remainingSpace = math.max(0.0, freeSpace - usedSpace);
       double leadingSpace;
       double betweenSpace;
  
positive.code:         break;
      }
  
      Size desiredSize;
      switch (_direction) {
        case FlexDirection.horizontal:
          desiredSize = new Size(mainSize, crossSize);
          size = constraints.constrain(desiredSize);
          crossSize = size.height;
          break;
        case FlexDirection.vertical:
          desiredSize = new Size(crossSize, mainSize);
          size = constraints.constrain(new Size(crossSize, mainSize));
          crossSize = size.width;
          break;
      }
      _overflowOccurredDuringLayout = desiredSize != size;
  
      // Position elements
      double childMainPosition = leadingSpace;
  
negative.code:       }
        child = child.parentData.nextSibling;
      }
      _overflow = math.max(0.0, -freeSpace);
      freeSpace = math.max(0.0, freeSpace);
  
      // Steps 4-5. Distribute remaining space to flexible children.
      double spacePerFlex = totalFlex > 0 ? (freeSpace / totalFlex) : 0.0;
  