diff --git a/components/layout/display_list/builder.rs b/components/layout/display_list/builder.rs
index 8d2354dbb191..00db9d10cc27 100644
--- a/components/layout/display_list/builder.rs
+++ b/components/layout/display_list/builder.rs
@@ -20,7 +20,7 @@ use display_list::items::{BaseDisplayItem, BLUR_INFLATION_FACTOR, ClipScrollNode
 use display_list::items::{ClipScrollNodeIndex, ClipScrollNodeType, ClippingAndScrolling};
 use display_list::items::{ClippingRegion, DisplayItem, DisplayItemMetadata, DisplayList};
 use display_list::items::{DisplayListSection, CommonDisplayItem};
-use display_list::items::{IframeDisplayItem, LineDisplayItem, OpaqueNode};
+use display_list::items::{IframeDisplayItem, OpaqueNode};
 use display_list::items::{PopAllTextShadowsDisplayItem, PushTextShadowDisplayItem};
 use display_list::items::{StackingContext, StackingContextType, StickyFrameData};
 use display_list::items::{TextOrientation, WebRenderImageInfo};
@@ -1573,11 +1573,17 @@ impl FragmentDisplayListBuilding for Fragment {
             style.get_cursor(CursorKind::Default),
             DisplayListSection::Content,
         );
-        state.add_display_item(DisplayItem::Line(Box::new(LineDisplayItem {
-            base: base,
-            color: ColorF::rgb(0, 200, 0),
-            style: LineStyle::Dashed,
-        })));
+        // TODO(gw): Use a better estimate for wavy line thickness.
+        let wavy_line_thickness = (0.33 * base.bounds.size.height).ceil();
+        state.add_display_item(DisplayItem::Line(CommonDisplayItem::new(
+            base,
+            webrender_api::LineDisplayItem {
+                orientation: webrender_api::LineOrientation::Horizontal,
+                wavy_line_thickness,
+                color: ColorF::rgb(0, 200, 0),
+                style: LineStyle::Dashed,
+            },
+        )));
     }
 
     fn build_debug_borders_around_fragment(
@@ -2272,11 +2278,17 @@ impl FragmentDisplayListBuilding for Fragment {
             DisplayListSection::Content,
         );
 
-        state.add_display_item(DisplayItem::Line(Box::new(LineDisplayItem {
-            base: base,
-            color: color.to_layout(),
-            style: LineStyle::Solid,
-        })));
+        // TODO(gw): Use a better estimate for wavy line thickness.
+        let wavy_line_thickness = (0.33 * base.bounds.size.height).ceil();
+        state.add_display_item(DisplayItem::Line(CommonDisplayItem::new(
+            base,
+            webrender_api::LineDisplayItem {
+                orientation: webrender_api::LineOrientation::Horizontal,
+                wavy_line_thickness,
+                color: color.to_layout(),
+                style: LineStyle::Solid,
+            },
+        )));
     }
 
     fn unique_id(&self) -> u64 {
diff --git a/components/layout/display_list/items.rs b/components/layout/display_list/items.rs
index 51e44e25cdbe..13de13607378 100644
--- a/components/layout/display_list/items.rs
+++ b/components/layout/display_list/items.rs
@@ -23,10 +23,10 @@ use std::collections::HashMap;
 use std::f32;
 use std::fmt;
 use webrender_api as wr;
-use webrender_api::{BorderRadius, ClipMode, ColorF};
+use webrender_api::{BorderRadius, ClipMode};
 use webrender_api::{ComplexClipRegion, ExternalScrollId, FilterOp};
 use webrender_api::{GlyphInstance, GradientStop, ImageKey, LayoutPoint};
-use webrender_api::{LayoutRect, LayoutSize, LayoutTransform, LayoutVector2D, LineStyle};
+use webrender_api::{LayoutRect, LayoutSize, LayoutTransform, LayoutVector2D};
 use webrender_api::{MixBlendMode, ScrollSensitivity, Shadow};
 use webrender_api::{StickyOffsetBounds, TransformStyle};
 
@@ -380,7 +380,7 @@ pub enum DisplayItem {
     Border(Box<CommonDisplayItem<wr::BorderDisplayItem, Vec<GradientStop>>>),
     Gradient(Box<CommonDisplayItem<wr::GradientDisplayItem, Vec<GradientStop>>>),
     RadialGradient(Box<CommonDisplayItem<wr::RadialGradientDisplayItem, Vec<GradientStop>>>),
-    Line(Box<LineDisplayItem>),
+    Line(Box<CommonDisplayItem<wr::LineDisplayItem>>),
     BoxShadow(Box<CommonDisplayItem<wr::BoxShadowDisplayItem>>),
     PushTextShadow(Box<PushTextShadowDisplayItem>),
     PopAllTextShadows(Box<PopAllTextShadowsDisplayItem>),
@@ -678,18 +678,6 @@ pub struct IframeDisplayItem {
     pub iframe: PipelineId,
 }
 
-/// Paints a line segment.
-#[derive(Clone, Serialize)]
-pub struct LineDisplayItem {
-    pub base: BaseDisplayItem,
-
-    /// The line segment color.
-    pub color: ColorF,
-
-    /// The line segment style.
-    pub style: LineStyle,
-}
-
 #[derive(Clone, Serialize)]
 pub struct CommonDisplayItem<T, U = ()> {
     pub base: BaseDisplayItem,
@@ -865,27 +853,3 @@ impl WebRenderImageInfo {
 
 /// The type of the scroll offset list. This is only populated if WebRender is in use.
 pub type ScrollOffsetMap = HashMap<ExternalScrollId, Vector2D<f32>>;
-
-pub trait SimpleMatrixDetection {
-    fn is_identity_or_simple_translation(&self) -> bool;
-}
-
-impl SimpleMatrixDetection for LayoutTransform {
-    #[inline]
-    fn is_identity_or_simple_translation(&self) -> bool {
-        let (_0, _1) = (0.0, 1.0);
-        self.m11 == _1 &&
-            self.m12 == _0 &&
-            self.m13 == _0 &&
-            self.m14 == _0 &&
-            self.m21 == _0 &&
-            self.m22 == _1 &&
-            self.m23 == _0 &&
-            self.m24 == _0 &&
-            self.m31 == _0 &&
-            self.m32 == _0 &&
-            self.m33 == _1 &&
-            self.m34 == _0 &&
-            self.m44 == _1
-    }
-}
diff --git a/components/layout/display_list/webrender_helpers.rs b/components/layout/display_list/webrender_helpers.rs
index 4c5fa9df8c29..9fb1dd001e24 100644
--- a/components/layout/display_list/webrender_helpers.rs
+++ b/components/layout/display_list/webrender_helpers.rs
@@ -131,14 +131,7 @@ impl WebRenderDisplayItemConverter for DisplayItem {
                 );
             },
             DisplayItem::Line(ref item) => {
-                builder.push_line(
-                    &self.prim_info(),
-                    // TODO(gw): Use a better estimate for wavy line thickness.
-                    (0.33 * item.base.bounds.size.height).ceil(),
-                    webrender_api::LineOrientation::Horizontal,
-                    &item.color,
-                    item.style,
-                );
+                builder.push_item(SpecificDisplayItem::Line(item.item), &self.prim_info());
             },
             DisplayItem::BoxShadow(ref item) => {
                 builder.push_item(SpecificDisplayItem::BoxShadow(item.item), &self.prim_info());