Replace easing function values with CSS defaults (Easing tokens phase 1)

[johanstromqvist]

Issue broken out of #4746

1. Add the missing tokens ease-in-out and linear
2. Update the cubic bezier values of ease-in and ease-out
3. Replace the two instances of ease-excite with ease
4. Remove ease-excite

End result: CSS default values.

Name	Equivalent to
ease	cubic-bezier(0.25, 0.1, 0.25, 1)
ease-in	cubic-bezier(0.42, 0, 1, 1)
ease-out	cubic-bezier(0, 0, 0.58, 1)
ease-in-out	cubic-bezier(0.42, 0, 0.58, 1)
linear	cubic-bezier(0, 0, 1, 1)