Support parsing moz-specific matrix functions in prefixed transform property

[upsuper]

Gecko supports a different syntax for matrix and matrix3d function in -moz-transform property. Specifically, when the property is prefixed, it accepts <length> in addition to <number> for transition parts of the matrix functions.

That says, this kind of syntax are valid for -moz-transform:

-moz-transform: matrix(1 0 0 1 5px -5px);
-moz-transform: matrix2d(1 0 0 0
                         0 1 0 0
                         0 0 1 0
                         1px 2px 3px 1);

while in transform, only <number>s are allowed.