When a native OS X colorpicker is opened from a click on a <input type="color">, a color selection in the NSNamedColorSpace color space is never handled. To verify that, open such a colorpicker, switch to the "Color Palettes" tab, select "Developer" in the dropdown and click any system color. The fix is pretty simple and requires a conversion in nsColorPicker::Update. I understand a fix there will only select the RGB value of the chosen system color *at the time of the selection* but that's still better than no result at all.
Comment on attachment 8718030 [details] [diff] [review] trivial fix Looks good to me. Not sure why you didn't request review.
Pushed by email@example.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/bd03c5af655d Correctly handle colors from named color spaces in the native color picker. r=mstange