title: GridView.builder creates page that scrolls endlessly
body: <p>Trying to use an API to build the grid. Everything renders fine but after the last row of tiles the page goes blank &amp; just keeps scrolling &amp; scrolling &amp;... the grid is built like so:</p>
  
  <pre><code>body: new GridView.builder(
        gridDelegate: new SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: (orientation == Orientation.portrait) ? 2 : 3),
        itemBuilder: (BuildContext context, int index) {
          return new Card(
            child: new GridTile(
              footer: new Text(data[index]['name']),
                child: new Text(data[index]['image']), //just for testing, will fill with image later
            ),
          );
        },
    )
  </code></pre>
  
  <p>The exception as I continually scroll further down the blank page with the last number (inclusive: 24) getting larger by multiples of 2 (24,26,28,etc).</p>
  
  <pre><code>I/flutter (11001): Another exception was thrown: RangeError (index): Invalid value: Not in range 0..23, inclusive: 24
  </code></pre>
  
  <p>Anyone seen this behavior with GridView.builder?</p>