diff --git a/components/style/values/computed/length.rs b/components/style/values/computed/length.rs
index 211c341d721..a83e86bd1e6 100644
--- a/components/style/values/computed/length.rs
+++ b/components/style/values/computed/length.rs
@@ -128,21 +128,27 @@ impl CalcLengthOrPercentage {
         self.length
     }
 
+    /// Return the percentage value as CSSFloat.
     #[inline]
-    #[allow(missing_docs)]
     pub fn percentage(&self) -> CSSFloat {
         self.percentage.map_or(0., |p| p.0)
     }
 
+    /// Convert the computed value into used value.
+    #[inline]
+    pub fn to_used_value(&self, container_len: Option<Au>) -> Option<Au> {
+        self.to_pixel_length(container_len).map(Au::from)
+    }
+
     /// If there are special rules for computing percentages in a value (e.g. the height property),
     /// they apply whenever a calc() expression contains percentages.
-    pub fn to_used_value(&self, container_len: Option<Au>) -> Option<Au> {
+    pub fn to_pixel_length(&self, container_len: Option<Au>) -> Option<Length> {
         match (container_len, self.percentage) {
             (Some(len), Some(percent)) => {
                 let pixel = self.length.px() + len.scale_by(percent.0).to_f32_px();
-                Some(Au::from_f32_px(self.clamping_mode.clamp(pixel)))
+                Some(Length::new(self.clamping_mode.clamp(pixel)))
             },
-            (_, None) => Some(Au::from(self.length())),
+            (_, None) => Some(self.length()),
             _ => None,
         }
     }
@@ -377,11 +383,16 @@ impl LengthOrPercentage {
 
     /// Returns the used value.
     pub fn to_used_value(&self, containing_length: Au) -> Au {
+        Au::from(self.to_pixel_length(containing_length))
+    }
+
+    /// Returns the used value as CSSPixelLength.
+    pub fn to_pixel_length(&self, containing_length: Au) -> Length {
         match *self {
-            LengthOrPercentage::Length(length) => Au::from(length),
-            LengthOrPercentage::Percentage(p) => containing_length.scale_by(p.0),
+            LengthOrPercentage::Length(length) => length,
+            LengthOrPercentage::Percentage(p) => containing_length.scale_by(p.0).into(),
             LengthOrPercentage::Calc(ref calc) => {
-                calc.to_used_value(Some(containing_length)).unwrap()
+                calc.to_pixel_length(Some(containing_length)).unwrap()
             },
         }
     }
diff --git a/components/style/values/computed/transform.rs b/components/style/values/computed/transform.rs
index 1923902b958..21c98c50d99 100644
--- a/components/style/values/computed/transform.rs
+++ b/components/style/values/computed/transform.rs
@@ -95,8 +95,8 @@ impl TransformList {
                 ComputedOperation::Translate(tx, ty, tz) => {
                     let (tx, ty) = match reference_box {
                         Some(relative_border_box) => {
-                            (tx.to_used_value(relative_border_box.size.width).to_f32_px(),
-                             ty.to_used_value(relative_border_box.size.height).to_f32_px())
+                            (tx.to_pixel_length(relative_border_box.size.width).px(),
+                             ty.to_pixel_length(relative_border_box.size.height).px())
                         },
                         None => {
                             // If we don't have reference box, we cannot resolve the used value,
diff --git a/tests/wpt/metadata-css/css-transforms-1_dev/html/transform-rounding-001.htm.ini b/tests/wpt/metadata-css/css-transforms-1_dev/html/transform-rounding-001.htm.ini
deleted file mode 100644
index c8859a8ce3f..00000000000
--- a/tests/wpt/metadata-css/css-transforms-1_dev/html/transform-rounding-001.htm.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[transform-rounding-001.htm]
-  type: reftest
-  expected: FAIL