[css-color][compat][css-text-decor] Are more variants of currentcolor needed?

So the spec for the currentcolor:
https://drafts.csswg.org/css-color-4/#currentcolor-color
says that currentcolor represents the value of the 'color' property.

The text-emphasis-color and text-decoration-color properties:
https://drafts.csswg.org/css-text-decor-3/#propdef-text-emphasis-color
https://drafts.csswg.org/css-text-decor-3/#propdef-text-decoration-color
use currentcolor as their initial value.

However, the compat spec introduces a -webkit-text-fill-color
property that overrides the color of text:
https://compat.spec.whatwg.org/#the-webkit-text-fill-color
which has proven to be needed for compatibily.  I believe Edge has
implemented it, and Gecko has an implementation and is working on
implementing the full set of changes needed to ship that
implementation.

In Chromium (and I presume WebKit, although I didn't test), the
-webkit-text-fill-color property also influences the color of
text-decorations.  See this test:
http://dbaron.org/css/test/2016/currentcolor

I presume that it should also influence the color of text-emphasis,
although neither Chromium nor Edge appears to implement
text-emphasis, and the patches to Gecko so far haven't done this
(although I think they should).

How should this be handled?  I see a few options:

 (1) Say that the 'currentcolor' value has different meaning for
 text-decoration-color and text-emphasis-color, and for those
 properties uses '-webkit-text-fill-color' instead of 'color'.

 (2) Introduce a new value, such as 'current-text-color' or
 'current-text-fill-color' (maybe without hyphens‽) that is the
 initial value of 'text-decoration-color' and 'text-emphasis-color'.

Again, I wrote a few tests for this at:
http://dbaron.org/css/test/2016/currentcolor
although I think more could probably be added.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
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