We purge it [here](https://github.com/facebook/react/blob/b11540ccb2321aeb7259fcf0b3a38aeeea35231d/src/isomorphic/ReactDebugTool.js#L88-L89) but this code doesn’t run because of the [early exit](https://github.com/facebook/react/blob/b11540ccb2321aeb7259fcf0b3a38aeeea35231d/src/isomorphic/ReactDebugTool.js#L53-L57).

Need to fix this and add a test case to make sure we don’t regress on it.

children: [],
            }],
          }, {
            displayName: 'Bar',
            children: [{
              displayName: 'h1',
              children: [{
                displayName: 'span',
                children: [{
                  displayName: '#text',
                  text: 'Hi,',
                }],
              }, {
                displayName: '#text',
                text: 'Mom',
              }],
            }],
          }, {
            displayName: 'a',
            children: [{
              displayName: '#text',
              text: 'Click me.',
            }],
          }],
        }],
      };
      assertTreeMatches([element, tree]);
    });
    it('ignores null children', () => {
      class Foo extends React.Component {