title: Creating markers with an icon of type google.maps.Symbol sometimes gives an error "Invalid value for property <icon>"
body: <p>I noticed some weird behavior when trying out vector icons in Maps API 3.9 as described here: <a href="https://developers.google.com/maps/documentation/javascript/overlays#VectorIcons" rel="nofollow">https://developers.google.com/maps/documentation/javascript/overlays#VectorIcons</a></p>
  
  <p>I created a test page (<a href="http://www.foxden.nl/test/symboltest1.html" rel="nofollow">http://www.foxden.nl/test/symboltest1.html</a>) with a vector icon which runs fine.</p>
  
  <p>However, in a second test (http://www.foxden.nl/test/symboltest2.html) I left away the script that draws the marker. When I then use Firefox's web console to add the marker, I get the following:</p>
  
  <pre><code>[16:03:18.483]     var marker = new google.maps.Marker({
                       position: new google.maps.LatLng(-25.363882, 131.044922),
                       icon: {
                         path: google.maps.SymbolPath.CIRCLE,
                         scale: 10
                       },
                       draggable: true,
                       map: map
                       });
  [16:03:18.486] Error: Invalid value for property &lt;icon&gt;: [object Object]
  </code></pre>
  
  <p>It works fine in Chrome's web console, but not in Firefox's console. And it's the exact same code.</p>
  
  <p>In a GWT application I get the same behavior. I have this function:</p>
  
  <pre><code>private native void createMarker(GoogleMap map, LatLng position) /*-{
      var marker = new $wnd.google.maps.Marker({
          position: position,
          icon: {
              path: $wnd.google.maps.SymbolPath.CIRCLE,
              scale: 10
          },
          map: map
      });
  }-*/;
  </code></pre>
  
  <p>Which gives me the same error:</p>
  
  <pre><code>com.google.gwt.core.client.JavaScriptException: (Error): Invalid value for property &lt;icon&gt;: [object Object]
  </code></pre>
  
  <p>Why does this happen, and is there any way I can avoid this problem?</p>