Fix demo page playground defaults

Author: bkis

index.html

@@ -212,7 +212,7 @@ <h2>Playground</h2>
           <label for="shapes">Shapes</label>
           <select id="shapes" value="null">
             <option value="null" selected>One random shape type</option>
-            <option value="[]" selected>All shape types</option>
+            <option value="[]">All shape types</option>
             <option value='["circle"]'>Circles only</option>
             <option value='["square"]'>Squares only</option>
             <option value='["line"]'>Lines only</option>