anchor.diff:          glPrimitives.vao = vao;
         }
       } else {
  -      context._bindIndexList(glIndexList);
  -
         // TODO: find better way than creating a new set every time.
         final unusedAttribLocations = context._enabledAttributeLocations.toSet();
   
  
positive.code: 
          context._vaoExtension.bindVertexArray(vao);
  
          if (glIndexList != null) {
            context._bindIndexList(glIndexList);
          }
  
          final attributes = glProgram.attributes;
          final attributesLength = attributes.length;
          final tables = new Set<AttributeDataTable>();
  
negative.code:     }
  
      if (glIndexList != null) {
        context._bindIndexList(glIndexList);
  
        final indexList = glIndexList.indexList;
  
        if (indexList.indexSize == IndexSize.unsignedByte) {
  