minor fixes

Author: rhulha

example/index.html

@@ -15,5 +15,6 @@
     <br><a href="test_obj.html">lightwave obj file viewer</a>
     <br><a href="test_sobel.html">test sobel edge detection shader</a>
     <br><a href="test_ssao.html">test screen space ambient occlusion (SSAO) shader</a>
+    <br><a href="test_plasma.html">test plasma shader</a>
   </body>
 </html>

lib/src/mesh_data.dart

@@ -27,7 +27,7 @@ class MeshData {
 
     if ( textureCoords != null && !(textureCoords is Float32List)) textureCoords = new Float32List.fromList(textureCoords);
 
-    if ( normals == null && !(normals is Float32List)) normals = new Float32List.fromList(normals);
+    if ( normals != null && !(normals is Float32List)) normals = new Float32List.fromList(normals);
 
     if (!(vertexIndices is Uint16List)) vertexIndices = new Uint16List.fromList(vertexIndices);
   }