Chrome and WebKit are debating over what the new web standard for "masonry" layout should be and how it should be defined.
Although, this is one of the most recognisable layouts, it's never been straightforward to implement.
WebKit wants masonry to be a part of display grid, but Chrome argues that it should be a completely different display method called "masonry".
The Chrome blog post above lists out the issues and confusions the new spec can cause if they were to move forward with WebKit's proposal.