code: function ( angle ) {
              var rad = this.DEG_TO_RAD * angle,
                  cosVal = Math.cos( rad ),
                  sinVal = Math.sin( rad ),
                  mtx = new $B.geom.Matrix( cosVal, sinVal, -sinVal, cosVal, 0, 0 );
              return this.concat( mtx );
          }
docs: Matrix 객체에 회전 변형을 적용
  @param	{Number}	angle	Degree
  @return {Matrix}