WebKit renders disable textarea text with different color specified in CSS when color is #000000. See differences between two textarea in problem page (http://jsfiddle.net/WR83J/) This bug is imported from http://crbug.com/91690
I think webkit shows gray color because this is how webkit shows disabled fields. I mean this is feature.
This old changeset for this bug http://trac.webkit.org/changeset/13929/trunk/WebCore/rendering/RenderTextField.cpp Currently it can be located at http://trac.webkit.org/browser/trunk/Source/WebCore/rendering/RenderTextControl.cpp#L47
Duplicate of bug 47429 and/or bug 54643. As mentioned above, it doesn't really sound like a bug.
*** This bug has been marked as a duplicate of bug 54643 ***