diff --git a/servo/components/layout/traversal.rs b/servo/components/layout/traversal.rs
index 692d956f0007..bd07e1f72bbc 100644
--- a/servo/components/layout/traversal.rs
+++ b/servo/components/layout/traversal.rs
@@ -65,7 +65,14 @@ impl<'lc, 'ln> DomTraversalContext<ServoLayoutNode<'ln>> for RecalcStyleAndConst
         }
     }
 
-    fn process_preorder(&self, node: ServoLayoutNode<'ln>) { recalc_style_at(&self.context, self.root, node); }
+    fn process_preorder(&self, node: ServoLayoutNode<'ln>) {
+        // FIXME(pcwalton): Stop allocating here. Ideally this should just be done by the HTML
+        // parser.
+        node.initialize_data();
+
+        recalc_style_at(&self.context, self.root, node);
+    }
+
     fn process_postorder(&self, node: ServoLayoutNode<'ln>) { construct_flows_at(&self.context, self.root, node); }
 }
 
diff --git a/servo/components/layout/wrapper.rs b/servo/components/layout/wrapper.rs
index 303c9f76943d..3c18e909baef 100644
--- a/servo/components/layout/wrapper.rs
+++ b/servo/components/layout/wrapper.rs
@@ -120,6 +120,19 @@ impl<'ln> ServoLayoutNode<'ln> {
             chain: self.chain,
         }
     }
+
+    pub fn initialize_data(self) {
+        if unsafe { self.borrow_data_unchecked() }.is_none() {
+            let ptr: NonOpaqueStyleAndLayoutData =
+                Box::into_raw(box RefCell::new(PrivateLayoutData::new()));
+            let opaque = OpaqueStyleAndLayoutData {
+                ptr: unsafe { NonZero::new(ptr as *mut ()) }
+            };
+            unsafe {
+                self.node.init_style_and_layout_data(opaque);
+            }
+        }
+    }
 }
 
 impl<'ln> TNode for ServoLayoutNode<'ln> {
@@ -158,20 +171,6 @@ impl<'ln> TNode for ServoLayoutNode<'ln> {
         OpaqueNodeMethods::from_jsmanaged(unsafe { self.get_jsmanaged() })
     }
 
-    fn initialize_data(self) {
-        let has_data = unsafe { self.borrow_data_unchecked().is_some() };
-        if !has_data {
-            let ptr: NonOpaqueStyleAndLayoutData =
-                Box::into_raw(box RefCell::new(PrivateLayoutData::new()));
-            let opaque = OpaqueStyleAndLayoutData {
-                ptr: unsafe { NonZero::new(ptr as *mut ()) }
-            };
-            unsafe {
-                self.node.init_style_and_layout_data(opaque);
-            }
-        }
-    }
-
     fn layout_parent_node(self, reflow_root: OpaqueNode) -> Option<ServoLayoutNode<'ln>> {
         if self.opaque() == reflow_root {
             None
diff --git a/servo/components/style/dom.rs b/servo/components/style/dom.rs
index badd4f310658..7d10b3949899 100644
--- a/servo/components/style/dom.rs
+++ b/servo/components/style/dom.rs
@@ -86,12 +86,6 @@ pub trait TNode : Sized + Copy + Clone {
     /// Converts self into an `OpaqueNode`.
     fn opaque(&self) -> OpaqueNode;
 
-    /// Initializes style and layout data for the node. No-op if the data is already
-    /// initialized.
-    ///
-    /// FIXME(pcwalton): Do this as part of fragment building instead of in a traversal.
-    fn initialize_data(self);
-
     /// While doing a reflow, the node at the root has no parent, as far as we're
     /// concerned. This method returns `None` at the reflow root.
     fn layout_parent_node(self, reflow_root: OpaqueNode) -> Option<Self>;
diff --git a/servo/components/style/traversal.rs b/servo/components/style/traversal.rs
index 386af02e5ef7..1afdcbb34c72 100644
--- a/servo/components/style/traversal.rs
+++ b/servo/components/style/traversal.rs
@@ -125,12 +125,6 @@ pub fn recalc_style_at<'a, N, C>(context: &'a C,
     where N: TNode,
           C: StyleContext<'a, <N::ConcreteElement as Element>::Impl>,
           <N::ConcreteElement as Element>::Impl: SelectorImplExt<ComputedValues=N::ConcreteComputedValues> + 'a {
-    // Initialize layout data.
-    //
-    // FIXME(pcwalton): Stop allocating here. Ideally this should just be done by the HTML
-    // parser.
-    node.initialize_data();
-
     // Get the parent node.
     let parent_opt = match node.parent_node() {
         Some(parent) if parent.is_element() => Some(parent),
diff --git a/servo/ports/geckolib/traversal.rs b/servo/ports/geckolib/traversal.rs
index 4e10d8c8fc85..f400377aeca9 100644
--- a/servo/ports/geckolib/traversal.rs
+++ b/servo/ports/geckolib/traversal.rs
@@ -80,7 +80,14 @@ impl<'lc, 'ln> DomTraversalContext<GeckoNode<'ln>> for RecalcStyleOnly<'lc> {
         }
     }
 
-    fn process_preorder(&self, node: GeckoNode<'ln>) { recalc_style_at(&self.context, self.root, node); }
+    fn process_preorder(&self, node: GeckoNode<'ln>) {
+        // FIXME(pcwalton): Stop allocating here. Ideally this should just be done by the HTML
+        // parser.
+        node.initialize_data();
+
+        recalc_style_at(&self.context, self.root, node);
+    }
+
     fn process_postorder(&self, _: GeckoNode<'ln>) {}
 }
 
diff --git a/servo/ports/geckolib/wrapper.rs b/servo/ports/geckolib/wrapper.rs
index b36e8fd74634..7a4125717c5e 100644
--- a/servo/ports/geckolib/wrapper.rs
+++ b/servo/ports/geckolib/wrapper.rs
@@ -81,6 +81,15 @@ impl<'ln> GeckoNode<'ln> {
             Gecko_GetNodeData(self.node) as NonOpaqueStyleData
         }
     }
+
+    pub fn initialize_data(self) {
+        unsafe {
+            if self.get_node_data().is_null() {
+                let ptr: NonOpaqueStyleData = Box::into_raw(box RefCell::new(PrivateStyleData::new()));
+                Gecko_SetNodeData(self.node, ptr as *mut ServoNodeData);
+            }
+        }
+    }
 }
 
 #[derive(Clone, Copy)]
@@ -132,15 +141,6 @@ impl<'ln> TNode for GeckoNode<'ln> {
         OpaqueNode(ptr)
     }
 
-    fn initialize_data(self) {
-        unsafe {
-            if self.get_node_data().is_null() {
-                let ptr: NonOpaqueStyleData = Box::into_raw(box RefCell::new(PrivateStyleData::new()));
-                Gecko_SetNodeData(self.node, ptr as *mut ServoNodeData);
-            }
-        }
-    }
-
     fn layout_parent_node(self, reflow_root: OpaqueNode) -> Option<GeckoNode<'ln>> {
         if self.opaque() == reflow_root {
             None