A gradient's first colour stop written at a unitless 0 is dropped, so repeating-radial-gradient(red 0, blue 10px) draws solid blue #584

Part of #552 (step 28, values read wrongly).

The audit recorded this as "repeating-radial-gradient() draws one solid colour". It does not: repeating radial gradients draw their rings. What fails is the audit's input, red 0. A first colour stop written with a unitless 0 position is taken for the gradient's angle and dropped, in linear and radial gradients alike.

Measured on gravitypdf at 60b82630, PHP 8.5.4, on a 60 × 30 mm block, rasterised.

Cause. Both parsers decide whether the first comma-separated part is a direction or a colour stop. A part whose last word is 0 counts as a direction, whatever comes before it (src/Gradient.php:651 and :676 in parseMozLinearGradient(), :804 in parseMozRadialGradient()). A bare 0 is a valid angle, and linear-gradient(0, red, blue) has to keep working. But red 0 is a colour stop, and its colour is lost. The one remaining stop is then drawn on its own.

#577 rewrites the angle handling in parseMozLinearGradient() but keeps this check.

Fix. Treat the first part as a direction only when its first word is not a colour. 0 alone stays an angle; red 0 is a stop at 0. Apply the same test in both parsers.

Tests. Each row above, reading the stops given to the shading function: red 0 in first place, a bare 0 angle before the stops, rgb(…) 0, and a repeating radial gradient with stops in px and in %.