title: Unicode dots not rendering in the openlayers map anymore after upgrading form version 4 to 6?
body: <p>I recently updated my openlayers version from 4.6.5 to the latest 6.4.3.</p>
  <p>After adjusting all the interfaces and imports, one of the layers, which rendered fine before the migration, does not show the unicode dots anymore.</p>
  <p>The layer creation:</p>
  <pre><code>new olLayer.Vector({
         source: new VectorSource({
                  format: new olFormat.GeoJSON(),
                  wrapX: this.options.tileServerLang === 'ja',
                  loader: (extent: Extent) =&gt; {
                      //loader code
                  },
                  strategy: bbox
              }),
              style: new olStyle.Style({
                  text: new olStyle.Text({
                      text: '\u25CF',
                      font: '12px FontAwesome',
                      textBaseline: 'Bottom',
                      fill: new olStyle.Fill({
                          color: 'black'
                      })
                  }),
                  zIndex: LayerFactory.zIndexes.data
              }),
              zIndex: LayerFactory.zIndexes.data,
              className: 'ol-layer dot-density'
          });
  </code></pre>
  <p>Looking into the features, it turns out, that</p>
  <ol>
  <li>the style for the features is correct (see 'text' property below is a unicode dot)</li>
  <li>there are features added to the source</li>
  </ol>
  <p><a href="https://i.stack.imgur.com/sEY7m.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/sEY7m.png" alt="enter image description here" /></a></p>
  <p>Some additional info:</p>
  <ol>
  <li>this has worked on openlayers 4</li>
  <li>other layers render just fine (e.g. the heatmap)</li>
  </ol>
  <p>Is there something missing? What could be the reason for those chars not showing up?</p>