<cubic-bezier-timing-function> abscissas must be in the [0, 1] range

[apasov]

According to the documentation the syntax is

cubic-bezier(x1, y1, x2, y2)

where:

x1, y1, x2, y2
Are values representing the abscissas, and ordinates of the P1 and P2 points defining the cubic Bézier curve. x1 and x2 must be in the range [0, 1] or the value is invalid.

These cubic Bézier curves definitions are invalid:

/* Abscissas must be in the [0, 1] range or 
   the curve is not a function of time. */
cubic-bezier(2.45, 0.6, 4, 0.1)    

/* Abscissas must be in the [0, 1] range or 
   the curve is not a function of time. */
cubic-bezier(-1.9, 0.3, -0.2, 2.1)

But css-tree treats them as valid:

Can anything be done about this or it is not in the scope of this package?

[apasov]

Now on mdn/data the syntax for cubic-bezier-timing-function is

ease | ease-in | ease-out | ease-in-out | cubic-bezier(<number [0,1]>, <number>, <number [0,1]>, <number>)

mdn/data#416