css: Export some color value api for tests

Export enough api to test color conversion and interpolation.

gtk/gtkcsscolorvalue.c

@@ -608,7 +608,7 @@ gtk_css_color_value_new_literal (const GdkRGBA *color)
   return value;
 }
 
-static GtkCssValue *
+GtkCssValue *
 gtk_css_color_value_new_color (GtkCssColorSpace color_space,
                                gboolean         serialize_as_rgb,
                                float            values[4],
@@ -1633,3 +1633,12 @@ gtk_css_color_value_get_rgba (const GtkCssValue *color)
 
   return &color->rgba;
 }
+
+const GtkCssColor *
+gtk_css_color_value_get_color (const GtkCssValue *color)
+{
+  g_assert (color->class == &GTK_CSS_VALUE_COLOR);
+  g_assert (color->type == COLOR_TYPE_COLOR);
+
+  return &color->color;
+}

gtk/gtkcsscolorvalueprivate.h

@@ -21,6 +21,7 @@
 #include "gtk/css/gtkcsstokenizerprivate.h"
 #include "gtk/css/gtkcssparserprivate.h"
 #include "gtkcssvalueprivate.h"
+#include "gtkcsscolorprivate.h"
 
 G_BEGIN_DECLS
 
@@ -37,6 +38,14 @@ GtkCssValue *   gtk_css_color_value_resolve             (GtkCssValue      *color
                                                          GtkCssValue      *current);
 const GdkRGBA * gtk_css_color_value_get_rgba            (const GtkCssValue *color) G_GNUC_CONST;
 
+GtkCssValue *   gtk_css_color_value_new_color           (GtkCssColorSpace color_space,
+                                                         gboolean         serialize_as_rgb,
+                                                         float            values[4],
+                                                         gboolean         missing[4]) G_GNUC_PURE;
+
+const GtkCssColor *
+                gtk_css_color_value_get_color           (const GtkCssValue *color) G_GNUC_CONST;
+
 
 G_END_DECLS