LibWeb/CSS: Add fixme for sRGB color interpolation

Corresponds to a0a9886063

Libraries/LibWeb/CSS/Interpolation.cpp

@@ -599,6 +599,10 @@ Color interpolate_color(Color from, Color to, float delta)
 {
     // https://drafts.csswg.org/css-color/#interpolation-space
     // If the host syntax does not define what color space interpolation should take place in, it defaults to Oklab.
+    // However, user agents must handle interpolation between legacy sRGB color formats (hex colors, named colors,
+    // rgb(), hsl() or hwb() and the equivalent alpha-including forms) in gamma-encoded sRGB space.  This provides
+    // Web compatibility; legacy sRGB content interpolates in the sRGB space by default.
+    // FIXME: Use srgb by default for these, once we can distinguish what form a color was specified in.
     auto from_oklab = from.to_oklab();
     auto to_oklab = to.to_oklab();