Note that System.uitypes also has the "web" color values in FPC 3.2+
High time! They were developed in the 80s by Netscape. Then organized and named by X11.
And introduced in CSS 3 around 2000.
There are at least 3 instances of the web colors in FPC+Lazarus, but nearly always local to a pacakge. This a historical problem caused by Delphi, because the color values orignally were part of units graphics which is already LCL/VCL.
UITYpes is a later extension to extract those color values out of the LCL on a sufficiently low (*) level that the rest of packages can use it. I hope in time all color tables will disappear or be replaced with references to it.
(*) rtl-objpas which has low package dependencies (only RTL)