title: Highcharts/Highstock flags series issue
body: <p>Why aren't ALL the flags in the withdrawals series showing? Please see the following JS fiddle: <a href="https://jsfiddle.net/lucianpurcarea/5zxa0jsm/13/" rel="nofollow noreferrer">https://jsfiddle.net/lucianpurcarea/5zxa0jsm/13/</a></p>
  
  <p>This is the part that creates the data array for the withdrawals series:</p>
  
  <pre><code>var withdrawalsFlags = [];
  for (var w = 0; w &lt; response.withdrawals.length; w++) {
    var title = "W:" + response.withdrawals[w][1] + "$";
    withdrawalsFlags.push({
      "x": response.withdrawals[w][0],
      "id": (response.withdrawals[w][0]),
      "title": title
    });
  }
  </code></pre>
  
  <p>In the fiddle that i prepared, the "title" on the withdrawals series is made up of "W: " + <em>dollar value</em> + "$". When this is the case, i see about 5 flags on the series. If i remove the "W:" i see more, if i remove the "$" at the end as well i see them all. </p>
  
  <p>If i zoom in on one specific section, i see all the flags present in that section. </p>
  
  <p>Thanks in advance to anyone taking a look at this! </p>