[css-transforms] interpolation of quaternions with t < 0 or t > 1

[hiikezoe]

https://www.w3.org/TR/2012/WD-css3-transforms-20120911/#matrix-values-interpolation

The spec limits interpolation parameter within [0, 1], but some cubic-bezier functions produce values out of the range. e.g. cubic-bezier(0,1.5,1,1.5).

[smfr]

This text is not in css-transforms-1, but we haven't decided how to divide the "Interpolation of Matrices" section between level 1 (2D only) and level 2 (3D).

[dirkschulze]

It seems that this was moved to transforms 2 now. At least the code is only part of level 2 anymore.