[cssom] Should <number> be serialized using scientific notation?

In [1], the serialization of scientific notation for <number>, it says:

A base-ten number using digits 0-9 (U+0030 to U+0039) in the shortest form possible, using "." to separate decimals (if any), rounding the value if necessary to not produce more than 6 decimals, preceded by "-" (U+002D) if it is negative.

Note: scientific notation is not used.

I think this is a little bit ambiguous for scientific notation. For a very long number, like a max float (3.40282e+38), all the browsers (i.e. Chrome, Firefox, Safari) still serialize the scientific notation.
e.g.

div {
  animation-timing-function: cubic-bezier(0, 3.40282e+38, 0, 0);
}
console.log(window.getComputedStyle(div).animationTimingFunction); // the output is "cubic-bezier(0, 3.40282e+38, 0, 0)" in all the browsers.

Just want to know should we update the spec or all the implementations of browser are incorrect?
Besides, if we want to update the spec, should we use "+" sign in scientific notation? (i.e. Use 3.40282e38, instead of 3.40282e+38, because shorter serialization is preferred.)

[1] https://drafts.csswg.org/cssom/#serializing-css-values

Read the CSSOM “serializing CSS values” section linked in the issue, then compare its scientific-notation wording with the reported computed-style behavior in Chrome, Firefox, and Safari. Done means resolving whether the specification or implementations are incorrect and documenting the decision, including whether a plus sign is required in the notation.