glClearColor = function ( r, g, b, a ) {

		if ( _premultipliedAlpha === true ) {

			r *= a; g *= a; b *= a;

		}

		_gl.clearColor( r, g, b, a );

	}
@author supereggbert / http://www.paulbrunt.co.uk/
@author mrdoob / http://mrdoob.com/
@author alteredq / http://alteredqualia.com/
@author szimek / https://github.com/szimek/