Terms of Use link missing in Bing attribution

Not sure if this is an issue, or something changed in the way we are using Bing. But compare:

```
<!doctype html>
<html lang="en">
  <head>
    <link rel="stylesheet" href="http://ol3js.org/en/master/build/ol.css" type="text/css">
    <style>
      .map {
        height: 256px;
        width: 512px;
      }
      .ol-attribution ul, .ol-attribution a {
        color: black;
      }
    </style>
    <script src="http://ol3js.org/en/master/build/ol-simple.js" type="text/javascript"></script>
    <title>OpenLayers 3 example</title>
  </head>
  <body>
    <h1>My Map</h1>
    <div id="map" class="map"></div>
    <script type="text/javascript">
      var map = new ol.Map({
        target: 'map',
        renderer: ol.RendererHint.CANVAS,
        layers: [
          new ol.layer.Tile({
            source: new ol.source.BingMaps({
              style: 'Road',
              key: 'Ak-dzM4wZjSqTlzveKz5u0d4IQ4bRzVI309GxmkgSVr1ewS6iPSrOvOKhA-CJlm3'
            })
          })
        ],
        view: new ol.View2D({
          center: ol.proj.transform([-71.147, 42.47], 'EPSG:4326', 'EPSG:3857'),
          zoom: 11
        })
      });
    </script>
  </body>
</html>
```

with: http://dev.openlayers.org/releases/OpenLayers-2.13.1/examples/bing-tiles.html