**Do you want to request a *feature* or report a *bug*?**
bug

**What is the current behavior?**
In normal rendering, you can memoize a class-based component: https://jsfiddle.net/586ea3cx/

With the shallow renderer, it seems like you can't: https://jsfiddle.net/odj217Lv/1/

This might be blocking https://github.com/airbnb/enzyme/pull/1914, in which tests are failing with `Cannot call a class as a function`. (it's tough to repro stuff with the shallow renderer)
lastRenderPhaseUpdate.next = update;
      }
    } else {
      
      
      
    }
  }
  _createWorkInProgressHook(): Hook {
    if (this._workInProgressHook === null) {
      
      if (this._firstWorkInProgressHook === null) {
        this._isReRender = false;
        this._firstWorkInProgressHook = this._workInProgressHook = createHook();
      } else {
        
        this._isReRender = true;
        this._workInProgressHook = this._firstWorkInProgressHook;
      }
    } else {
      if (this._workInProgressHook.next === null) {
        this._isReRender = false;
        
        this._workInProgressHook = (this
          ._workInProgressHook: any).next = createHook();
      } else {
        
        this._isReRender = true;
        this._workInProgressHook = this._workInProgressHook.next;
      }