title: jqplot.CanvasAxisTickRenderer throws Uncaught TypeError
body: <p>I am using jqplot to display my bar char.</p>
  
  <p>The bar chart worked fine until I added tickRenderer and tickOptions.  </p>
  
  <p>Now I get the following error: <strong>Uncaught TypeError: undefined is not a function</strong></p>
  
  <p>Here is my code</p>
  
  <pre><code>plot3 = $.jqplot('chart3', [s2, s3], {
      stackSeries: true,
      seriesDefaults: {
          renderer: $.jqplot.BarRenderer,
          rendererOptions: {
              highlightMouseDown: true
          },
          pointLabels: {show: true}
      },
      legend: {
          show: true,
          location: 'e',
          placement: 'outside'
      },
      axes: {
          xaxis: {
              renderer: $.jqplot.CategoryAxisRenderer,
              ticks: ticks,
              tickRenderer: $.jqplot.CanvasAxisTickRenderer ,
              tickOptions: {
                  angle: -90,
                  fontSize: '10pt'
              }
          }
      }
  });
  </code></pre>