updateUBOMapping method 
    
      
void
updateUBOMapping(
 - UniformsGroup uniformsGroup, 
- Program program
) 
    
    
  Implementation
  void updateUBOMapping(UniformsGroup uniformsGroup, Program program ) {
	dynamic mapping = uboProgramMap.get( program );
	if ( mapping == null ) {
		mapping = WeakMap();
		uboProgramMap.set( program, mapping );
	}
	dynamic blockIndex = mapping.get( uniformsGroup );
	if ( blockIndex == null ) {
		blockIndex = gl.getUniformBlockIndex( program, uniformsGroup.name );
		mapping.set( uniformsGroup, blockIndex );
	}
}