Add get_initial_specified_value to many longhands

components/style/values/specified/length.rs

@@ -344,6 +344,12 @@ impl NoCalcLength {
         *self == NoCalcLength::Absolute(Au(0))
     }
 
+    #[inline]
+    /// Returns a `medium` length.
+    pub fn medium() -> NoCalcLength {
+        NoCalcLength::Absolute(Au::from_px(FONT_MEDIUM_PX))
+    }
+
     /// Get an absolute length from a px value.
     #[inline]
     pub fn from_px(px_value: CSSFloat) -> NoCalcLength {

components/style/values/specified/mod.rs

@@ -78,6 +78,27 @@ impl ToCss for CSSColor {
     }
 }
 
+impl CSSColor {
+    #[inline]
+    /// Returns currentcolor value.
+    pub fn currentcolor() -> CSSColor {
+        CSSColor {
+            parsed: cssparser::Color::CurrentColor,
+            authored: None,
+        }
+    }
+
+    #[inline]
+    /// Returns transparent value.
+    pub fn transparent() -> CSSColor {
+        CSSColor {
+            parsed: cssparser::Color::RGBA(cssparser::RGBA::transparent()),
+            // This should probably be "transparent", but maybe it doesn't matter.
+            authored: None,
+        }
+    }
+}
+
 #[derive(Clone, PartialEq, Debug)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]