fix(view): change ViewPort to add View synchronously

  Before:

      viewPort.insert(a);
      viewPort.remove(a);

      viewPort.views == [a]

  After:

      viewPort.insert(a);
      viewPort.remove(a);

      viewPort.views == []
Looks like the right thing to do, especially since that's how both `remove` and `move` work - updating the internal list before the DOM writes.

However, this might brake someone depending on it, so lets' see if clients tests work with this.