`ReactServerRenderingTransaction` doesn’t have a `checkpoint()`, so any component with `handleError()` crashes during server rendering. I tested on 15, but pretty sure this is in master as well.

Fiddle: https://jsfiddle.net/un1nqs0w/

cc @jimfb 

render() {
        throw new Error('Always broken.');
      }
    }
    class BrokenUnmount extends React.Component {
      render() {
        return <div />;
      }
      componentWillUnmount() {
        throw new Error('Always broken.');
      }
    }
    var container = document.createElement('div');
    ReactDOM.render(
      <ErrorBoundary>
        <BrokenUnmount />
        <BrokenRender />
        <BrokenUnmount />
      </ErrorBoundary>,
      container
    );
    ReactDOM.unmountComponentAtNode(container);
  });
  it('expect uneventful render to succeed', function() {
    class Boundary extends React.Component {