diff --git a/components/script/dom/characterdata.rs b/components/script/dom/characterdata.rs
index bc1106f94cc..4f10e7d39f4 100644
--- a/components/script/dom/characterdata.rs
+++ b/components/script/dom/characterdata.rs
@@ -8,6 +8,7 @@ use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::CharacterDataBinding::CharacterDataMethods;
 use dom::bindings::codegen::InheritTypes::{CharacterDataDerived, ElementCast};
 use dom::bindings::codegen::InheritTypes::NodeCast;
+use dom::bindings::codegen::UnionTypes::NodeOrString;
 use dom::bindings::error::{Fallible, ErrorResult};
 use dom::bindings::error::Error::IndexSize;
 use dom::bindings::js::{JSRef, LayoutJS, Temporary};
@@ -118,6 +119,21 @@ impl<'a> CharacterDataMethods for JSRef<'a, CharacterData> {
         Ok(())
     }
 
+    // https://dom.spec.whatwg.org/#dom-childnode-before
+    fn Before(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).before(nodes)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-childnode-after
+    fn After(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).after(nodes)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-childnode-replacewith
+    fn ReplaceWith(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).replace_with(nodes)
+    }
+
     // https://dom.spec.whatwg.org/#dom-childnode-remove
     fn Remove(self) {
         let node: JSRef<Node> = NodeCast::from_ref(self);
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index bff8ea0cdba..bab20db68ca 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -19,6 +19,7 @@ use dom::bindings::codegen::InheritTypes::{HTMLAnchorElementDerived, HTMLAppletE
 use dom::bindings::codegen::InheritTypes::{HTMLAreaElementDerived, HTMLEmbedElementDerived};
 use dom::bindings::codegen::InheritTypes::{HTMLFormElementDerived, HTMLImageElementDerived};
 use dom::bindings::codegen::InheritTypes::{HTMLScriptElementDerived, CharacterDataCast};
+use dom::bindings::codegen::UnionTypes::NodeOrString;
 use dom::bindings::error::{ErrorResult, Fallible};
 use dom::bindings::error::Error::{NotSupported, InvalidCharacter, Security};
 use dom::bindings::error::Error::HierarchyRequest;
@@ -223,6 +224,8 @@ pub trait DocumentHelpers<'a> {
                           button: MouseButton, point: Point2D<f32>);
     fn dispatch_key_event(self, key: Key, state: KeyState,
         modifiers: KeyModifiers, compositor: &mut Box<ScriptListener+'static>);
+    fn node_from_nodes_and_strings(self, nodes: Vec<NodeOrString>)
+                                   -> Fallible<Temporary<Node>>;
 
     /// Handles a mouse-move event coming from the compositor.
     fn handle_mouse_move_event(self,
@@ -702,6 +705,34 @@ impl<'a> DocumentHelpers<'a> for JSRef<'a, Document> {
         window.r().reflow(ReflowGoal::ForDisplay, ReflowQueryType::NoQuery, ReflowReason::KeyEvent);
     }
 
+    fn node_from_nodes_and_strings(self, nodes: Vec<NodeOrString>)
+                                   -> Fallible<Temporary<Node>> {
+        if nodes.len() == 1 {
+            match nodes.into_iter().next().unwrap() {
+                NodeOrString::eNode(node) => Ok(Temporary::from_unrooted(node)),
+                NodeOrString::eString(string) => {
+                    Ok(NodeCast::from_temporary(self.CreateTextNode(string)))
+                },
+            }
+        } else {
+            let fragment = NodeCast::from_temporary(self.CreateDocumentFragment()).root();
+            for node in nodes.into_iter() {
+                match node {
+                    NodeOrString::eNode(node) => {
+                        try!(fragment.r().AppendChild(node.root().r()));
+                    },
+                    NodeOrString::eString(string) => {
+                        let node = NodeCast::from_temporary(self.CreateTextNode(string)).root();
+                        // No try!() here because appending a text node
+                        // should not fail.
+                        fragment.r().AppendChild(node.r()).unwrap();
+                    }
+                }
+            }
+            Ok(Temporary::from_rooted(fragment.r()))
+        }
+    }
+
     fn set_current_script(self, script: Option<JSRef<HTMLScriptElement>>) {
         self.current_script.assign(script);
     }
@@ -1377,6 +1408,16 @@ impl<'a> DocumentMethods for JSRef<'a, Document> {
         NodeCast::from_ref(self).child_elements().count() as u32
     }
 
+    // https://dom.spec.whatwg.org/#dom-parentnode-prepend
+    fn Prepend(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).prepend(nodes)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-parentnode-append
+    fn Append(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).append(nodes)
+    }
+
     // https://dom.spec.whatwg.org/#dom-parentnode-queryselector
     fn QuerySelector(self, selectors: DOMString) -> Fallible<Option<Temporary<Element>>> {
         let root: JSRef<Node> = NodeCast::from_ref(self);
diff --git a/components/script/dom/documentfragment.rs b/components/script/dom/documentfragment.rs
index 43af033a0fb..51f7fa48571 100644
--- a/components/script/dom/documentfragment.rs
+++ b/components/script/dom/documentfragment.rs
@@ -7,8 +7,9 @@ use dom::bindings::codegen::Bindings::DocumentFragmentBinding::DocumentFragmentM
 use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use dom::bindings::codegen::InheritTypes::DocumentFragmentDerived;
 use dom::bindings::codegen::InheritTypes::{ElementCast, NodeCast};
+use dom::bindings::codegen::UnionTypes::NodeOrString;
 use dom::bindings::js::{JSRef, Temporary};
-use dom::bindings::error::Fallible;
+use dom::bindings::error::{ErrorResult, Fallible};
 use dom::bindings::global::GlobalRef;
 use dom::document::Document;
 use dom::element::Element;
@@ -73,6 +74,16 @@ impl<'a> DocumentFragmentMethods for JSRef<'a, DocumentFragment> {
         NodeCast::from_ref(self).child_elements().count() as u32
     }
 
+    // https://dom.spec.whatwg.org/#dom-parentnode-prepend
+    fn Prepend(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).prepend(nodes)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-parentnode-append
+    fn Append(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).append(nodes)
+    }
+
     // https://dom.spec.whatwg.org/#dom-parentnode-queryselector
     fn QuerySelector(self, selectors: DOMString) -> Fallible<Option<Temporary<Element>>> {
         let root: JSRef<Node> = NodeCast::from_ref(self);
diff --git a/components/script/dom/documenttype.rs b/components/script/dom/documenttype.rs
index c8e3dfaa40e..b5fd4300b70 100644
--- a/components/script/dom/documenttype.rs
+++ b/components/script/dom/documenttype.rs
@@ -5,6 +5,8 @@
 use dom::bindings::codegen::Bindings::DocumentTypeBinding;
 use dom::bindings::codegen::Bindings::DocumentTypeBinding::DocumentTypeMethods;
 use dom::bindings::codegen::InheritTypes::{DocumentTypeDerived, NodeCast};
+use dom::bindings::codegen::UnionTypes::NodeOrString;
+use dom::bindings::error::ErrorResult;
 use dom::bindings::js::{JSRef, Temporary};
 use dom::document::Document;
 use dom::eventtarget::{EventTarget, EventTargetTypeId};
@@ -87,6 +89,21 @@ impl<'a> DocumentTypeMethods for JSRef<'a, DocumentType> {
         self.system_id.clone()
     }
 
+    // https://dom.spec.whatwg.org/#dom-childnode-before
+    fn Before(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).before(nodes)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-childnode-after
+    fn After(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).after(nodes)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-childnode-replacewith
+    fn ReplaceWith(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).replace_with(nodes)
+    }
+
     // https://dom.spec.whatwg.org/#dom-childnode-remove
     fn Remove(self) {
         let node: JSRef<Node> = NodeCast::from_ref(self);
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index f4f70020cde..24eda14cab5 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -23,6 +23,7 @@ use dom::bindings::codegen::InheritTypes::{HTMLTableElementDerived, HTMLTableCel
 use dom::bindings::codegen::InheritTypes::{HTMLTableRowElementDerived, HTMLTextAreaElementDerived};
 use dom::bindings::codegen::InheritTypes::{HTMLTableSectionElementDerived, NodeCast};
 use dom::bindings::codegen::InheritTypes::HTMLAnchorElementCast;
+use dom::bindings::codegen::UnionTypes::NodeOrString;
 use dom::bindings::error::{ErrorResult, Fallible};
 use dom::bindings::error::Error::{InvalidCharacter, Syntax};
 use dom::bindings::error::Error::NoModificationAllowed;
@@ -1292,6 +1293,16 @@ impl<'a> ElementMethods for JSRef<'a, Element> {
         NodeCast::from_ref(self).child_elements().count() as u32
     }
 
+    // https://dom.spec.whatwg.org/#dom-parentnode-prepend
+    fn Prepend(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).prepend(nodes)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-parentnode-append
+    fn Append(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).append(nodes)
+    }
+
     // https://dom.spec.whatwg.org/#dom-parentnode-queryselector
     fn QuerySelector(self, selectors: DOMString) -> Fallible<Option<Temporary<Element>>> {
         let root: JSRef<Node> = NodeCast::from_ref(self);
@@ -1304,6 +1315,21 @@ impl<'a> ElementMethods for JSRef<'a, Element> {
         root.query_selector_all(selectors)
     }
 
+    // https://dom.spec.whatwg.org/#dom-childnode-before
+    fn Before(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).before(nodes)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-childnode-after
+    fn After(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).after(nodes)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-childnode-replacewith
+    fn ReplaceWith(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        NodeCast::from_ref(self).replace_with(nodes)
+    }
+
     // https://dom.spec.whatwg.org/#dom-childnode-remove
     fn Remove(self) {
         let node: JSRef<Node> = NodeCast::from_ref(self);
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index 9d7c8b7e6e1..ca7d7598480 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -19,8 +19,9 @@ use dom::bindings::codegen::InheritTypes::{ElementCast, NodeCast, ElementDerived
 use dom::bindings::codegen::InheritTypes::{HTMLLegendElementDerived, HTMLFieldSetElementDerived};
 use dom::bindings::codegen::InheritTypes::{HTMLOptGroupElementDerived, NodeBase, NodeDerived};
 use dom::bindings::codegen::InheritTypes::{ProcessingInstructionCast, TextCast};
+use dom::bindings::codegen::UnionTypes::NodeOrString;
 use dom::bindings::conversions;
-use dom::bindings::error::Fallible;
+use dom::bindings::error::{ErrorResult, Fallible};
 use dom::bindings::error::Error::{NotFound, HierarchyRequest, Syntax};
 use dom::bindings::global::GlobalRef;
 use dom::bindings::js::{JS, JSRef, LayoutJS, RootedReference, Temporary, Root, Unrooted};
@@ -500,6 +501,12 @@ pub trait NodeHelpers {
     fn get_bounding_content_box(self) -> Rect<Au>;
     fn get_content_boxes(self) -> Vec<Rect<Au>>;
 
+    fn before(self, nodes: Vec<NodeOrString>) -> ErrorResult;
+    fn after(self, nodes: Vec<NodeOrString>) -> ErrorResult;
+    fn replace_with(self, nodes: Vec<NodeOrString>) -> ErrorResult;
+    fn prepend(self, nodes: Vec<NodeOrString>) -> ErrorResult;
+    fn append(self, nodes: Vec<NodeOrString>) -> ErrorResult;
+
     fn query_selector(self, selectors: DOMString) -> Fallible<Option<Temporary<Element>>>;
     #[allow(unsafe_code)]
     unsafe fn query_selector_iter(self, selectors: DOMString) -> Fallible<QuerySelectorIterator>;
@@ -513,6 +520,7 @@ pub trait NodeHelpers {
     fn teardown(self);
 
     fn parse_fragment(self, markup: DOMString) -> Fallible<Temporary<DocumentFragment>>;
+
 }
 
 impl<'a> NodeHelpers for JSRef<'a, Node> {
@@ -803,6 +811,80 @@ impl<'a> NodeHelpers for JSRef<'a, Node> {
         window_from_node(self).root().r().content_boxes_query(self.to_trusted_node_address())
     }
 
+    // https://dom.spec.whatwg.org/#dom-childnode-before
+    fn before(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        match self.parent_node().root() {
+            None => {
+                // Step 1.
+                Ok(())
+            },
+            Some(ref parent_node) => {
+                // Step 2.
+                let doc = self.owner_doc().root();
+                let node = try!(doc.r().node_from_nodes_and_strings(nodes)).root();
+                // Step 3.
+                Node::pre_insert(node.r(), parent_node.r(),
+                                 Some(self)).map(|_| ())
+            },
+        }
+    }
+
+    // https://dom.spec.whatwg.org/#dom-childnode-after
+    fn after(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        match self.parent_node().root() {
+            None => {
+                // Step 1.
+                Ok(())
+            },
+            Some(ref parent_node) => {
+                // Step 2.
+                let doc = self.owner_doc().root();
+                let node = try!(doc.r().node_from_nodes_and_strings(nodes)).root();
+                // Step 3.
+                // FIXME(https://github.com/servo/servo/issues/5720)
+                let next_sibling = self.next_sibling().root();
+                Node::pre_insert(node.r(), parent_node.r(),
+                                 next_sibling.r()).map(|_| ())
+            },
+        }
+    }
+
+    // https://dom.spec.whatwg.org/#dom-childnode-replacewith
+    fn replace_with(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        match self.parent_node().root() {
+            None => {
+                // Step 1.
+                Ok(())
+            },
+            Some(ref parent_node) => {
+                // Step 2.
+                let doc = self.owner_doc().root();
+                let node = try!(doc.r().node_from_nodes_and_strings(nodes)).root();
+                // Step 3.
+                parent_node.r().ReplaceChild(node.r(), self).map(|_| ())
+            },
+        }
+    }
+
+    // https://dom.spec.whatwg.org/#dom-parentnode-prepend
+    fn prepend(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        // Step 1.
+        let doc = self.owner_doc().root();
+        let node = try!(doc.r().node_from_nodes_and_strings(nodes)).root();
+        // Step 2.
+        let first_child = self.first_child().root();
+        Node::pre_insert(node.r(), self, first_child.r()).map(|_| ())
+    }
+
+    // https://dom.spec.whatwg.org/#dom-parentnode-append
+    fn append(self, nodes: Vec<NodeOrString>) -> ErrorResult {
+        // Step 1.
+        let doc = self.owner_doc().root();
+        let node = try!(doc.r().node_from_nodes_and_strings(nodes)).root();
+        // Step 2.
+        self.AppendChild(node.r()).map(|_| ())
+    }
+
     // https://dom.spec.whatwg.org/#dom-parentnode-queryselector
     fn query_selector(self, selectors: DOMString) -> Fallible<Option<Temporary<Element>>> {
         // Step 1.
diff --git a/components/script/dom/webidls/ChildNode.webidl b/components/script/dom/webidls/ChildNode.webidl
index de8d8271537..7205d08b05e 100644
--- a/components/script/dom/webidls/ChildNode.webidl
+++ b/components/script/dom/webidls/ChildNode.webidl
@@ -9,10 +9,12 @@
 
 [NoInterfaceObject]
 interface ChildNode {
-// Not implemented yet:
-//  void before((Node or DOMString)... nodes);
-//  void after((Node or DOMString)... nodes);
-//  void replace((Node or DOMString)... nodes);
+  [Throws]
+  void before((Node or DOMString)... nodes);
+  [Throws]
+  void after((Node or DOMString)... nodes);
+  [Throws]
+  void replaceWith((Node or DOMString)... nodes);
   void remove();
 };
 
diff --git a/components/script/dom/webidls/ParentNode.webidl b/components/script/dom/webidls/ParentNode.webidl
index 6d1d3037265..c7dc425a1fd 100644
--- a/components/script/dom/webidls/ParentNode.webidl
+++ b/components/script/dom/webidls/ParentNode.webidl
@@ -18,9 +18,10 @@ interface ParentNode {
   [Pure]
   readonly attribute unsigned long childElementCount;
 
-  // Not implemented yet
-  // void prepend((Node or DOMString)... nodes);
-  // void append((Node or DOMString)... nodes);
+  [Throws]
+  void prepend((Node or DOMString)... nodes);
+  [Throws]
+  void append((Node or DOMString)... nodes);
 
   //Element? query(DOMString relativeSelectors);
   //[NewObject]
diff --git a/tests/wpt/metadata/dom/interfaces.html.ini b/tests/wpt/metadata/dom/interfaces.html.ini
index 5edc29ea9a4..5d8828faeb0 100644
--- a/tests/wpt/metadata/dom/interfaces.html.ini
+++ b/tests/wpt/metadata/dom/interfaces.html.ini
@@ -96,12 +96,6 @@
   [Document interface: operation createTreeWalker(Node,unsigned long,NodeFilter)]
     expected: FAIL
 
-  [Document interface: operation prepend([object Object\],[object Object\])]
-    expected: FAIL
-
-  [Document interface: operation append([object Object\],[object Object\])]
-    expected: FAIL
-
   [Document interface: operation query(DOMString)]
     expected: FAIL
 
@@ -156,12 +150,6 @@
   [DocumentFragment interface: operation getElementById(DOMString)]
     expected: FAIL
 
-  [DocumentFragment interface: operation prepend([object Object\],[object Object\])]
-    expected: FAIL
-
-  [DocumentFragment interface: operation append([object Object\],[object Object\])]
-    expected: FAIL
-
   [DocumentFragment interface: operation query(DOMString)]
     expected: FAIL
 
@@ -174,15 +162,9 @@
   [DocumentFragment interface: calling getElementById(DOMString) on document.createDocumentFragment() with too few arguments must throw TypeError]
     expected: FAIL
 
-  [DocumentFragment interface: document.createDocumentFragment() must inherit property "prepend" with the proper type (5)]
-    expected: FAIL
-
   [DocumentFragment interface: calling prepend([object Object\],[object Object\]) on document.createDocumentFragment() with too few arguments must throw TypeError]
     expected: FAIL
 
-  [DocumentFragment interface: document.createDocumentFragment() must inherit property "append" with the proper type (6)]
-    expected: FAIL
-
   [DocumentFragment interface: calling append([object Object\],[object Object\]) on document.createDocumentFragment() with too few arguments must throw TypeError]
     expected: FAIL
 
@@ -198,21 +180,9 @@
   [DocumentFragment interface: calling queryAll(DOMString) on document.createDocumentFragment() with too few arguments must throw TypeError]
     expected: FAIL
 
-  [DocumentType interface: operation before([object Object\],[object Object\])]
-    expected: FAIL
-
-  [DocumentType interface: operation after([object Object\],[object Object\])]
-    expected: FAIL
-
-  [DocumentType interface: document.doctype must inherit property "before" with the proper type (3)]
-    expected: FAIL
-
   [DocumentType interface: calling before([object Object\],[object Object\]) on document.doctype with too few arguments must throw TypeError]
     expected: FAIL
 
-  [DocumentType interface: document.doctype must inherit property "after" with the proper type (4)]
-    expected: FAIL
-
   [DocumentType interface: calling after([object Object\],[object Object\]) on document.doctype with too few arguments must throw TypeError]
     expected: FAIL
 
@@ -234,24 +204,12 @@
   [Element interface: operation removeAttributeNode(Attr)]
     expected: FAIL
 
-  [Element interface: operation prepend([object Object\],[object Object\])]
-    expected: FAIL
-
-  [Element interface: operation append([object Object\],[object Object\])]
-    expected: FAIL
-
   [Element interface: operation query(DOMString)]
     expected: FAIL
 
   [Element interface: operation queryAll(DOMString)]
     expected: FAIL
 
-  [Element interface: operation before([object Object\],[object Object\])]
-    expected: FAIL
-
-  [Element interface: operation after([object Object\],[object Object\])]
-    expected: FAIL
-
   [Element interface: element must inherit property "hasAttributes" with the proper type (7)]
     expected: FAIL
 
@@ -285,15 +243,9 @@
   [Element interface: calling removeAttributeNode(Attr) on element with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Element interface: element must inherit property "prepend" with the proper type (31)]
-    expected: FAIL
-
   [Element interface: calling prepend([object Object\],[object Object\]) on element with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Element interface: element must inherit property "append" with the proper type (32)]
-    expected: FAIL
-
   [Element interface: calling append([object Object\],[object Object\]) on element with too few arguments must throw TypeError]
     expected: FAIL
 
@@ -309,15 +261,9 @@
   [Element interface: calling queryAll(DOMString) on element with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Element interface: element must inherit property "before" with the proper type (39)]
-    expected: FAIL
-
   [Element interface: calling before([object Object\],[object Object\]) on element with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Element interface: element must inherit property "after" with the proper type (40)]
-    expected: FAIL
-
   [Element interface: calling after([object Object\],[object Object\]) on element with too few arguments must throw TypeError]
     expected: FAIL
 
@@ -327,12 +273,6 @@
   [NamedNodeMap interface: operation setNamedItemNS(Attr)]
     expected: FAIL
 
-  [CharacterData interface: operation before([object Object\],[object Object\])]
-    expected: FAIL
-
-  [CharacterData interface: operation after([object Object\],[object Object\])]
-    expected: FAIL
-
   [Text interface object length]
     expected: FAIL
 
@@ -345,42 +285,24 @@
   [Text interface: calling splitText(unsigned long) on document.createTextNode("abc") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [CharacterData interface: document.createTextNode("abc") must inherit property "before" with the proper type (9)]
-    expected: FAIL
-
   [CharacterData interface: calling before([object Object\],[object Object\]) on document.createTextNode("abc") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [CharacterData interface: document.createTextNode("abc") must inherit property "after" with the proper type (10)]
-    expected: FAIL
-
   [CharacterData interface: calling after([object Object\],[object Object\]) on document.createTextNode("abc") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [CharacterData interface: xmlDoc.createProcessingInstruction("abc", "def") must inherit property "before" with the proper type (9)]
-    expected: FAIL
-
   [CharacterData interface: calling before([object Object\],[object Object\]) on xmlDoc.createProcessingInstruction("abc", "def") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [CharacterData interface: xmlDoc.createProcessingInstruction("abc", "def") must inherit property "after" with the proper type (10)]
-    expected: FAIL
-
   [CharacterData interface: calling after([object Object\],[object Object\]) on xmlDoc.createProcessingInstruction("abc", "def") with too few arguments must throw TypeError]
     expected: FAIL
 
   [Comment interface object length]
     expected: FAIL
 
-  [CharacterData interface: document.createComment("abc") must inherit property "before" with the proper type (9)]
-    expected: FAIL
-
   [CharacterData interface: calling before([object Object\],[object Object\]) on document.createComment("abc") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [CharacterData interface: document.createComment("abc") must inherit property "after" with the proper type (10)]
-    expected: FAIL
-
   [CharacterData interface: calling after([object Object\],[object Object\]) on document.createComment("abc") with too few arguments must throw TypeError]
     expected: FAIL
 
@@ -885,12 +807,6 @@
   [Document interface: xmlDoc must inherit property "createNodeIterator" with the proper type (25)]
     expected: FAIL
 
-  [Document interface: xmlDoc must inherit property "prepend" with the proper type (32)]
-    expected: FAIL
-
-  [Document interface: xmlDoc must inherit property "append" with the proper type (33)]
-    expected: FAIL
-
   [Document interface: xmlDoc must inherit property "query" with the proper type (34)]
     expected: FAIL
 
@@ -927,42 +843,18 @@
   [Comment interface: existence and properties of interface object]
     expected: FAIL
 
-  [DocumentType interface: operation replaceWith([object Object\],[object Object\])]
-    expected: FAIL
-
-  [DocumentType interface: document.doctype must inherit property "replaceWith" with the proper type (5)]
-    expected: FAIL
-
   [DocumentType interface: calling replaceWith([object Object\],[object Object\]) on document.doctype with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Element interface: operation replaceWith([object Object\],[object Object\])]
-    expected: FAIL
-
-  [Element interface: element must inherit property "replaceWith" with the proper type (41)]
-    expected: FAIL
-
   [Element interface: calling replaceWith([object Object\],[object Object\]) on element with too few arguments must throw TypeError]
     expected: FAIL
 
-  [CharacterData interface: operation replaceWith([object Object\],[object Object\])]
-    expected: FAIL
-
-  [CharacterData interface: document.createTextNode("abc") must inherit property "replaceWith" with the proper type (11)]
-    expected: FAIL
-
   [CharacterData interface: calling replaceWith([object Object\],[object Object\]) on document.createTextNode("abc") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [CharacterData interface: xmlDoc.createProcessingInstruction("abc", "def") must inherit property "replaceWith" with the proper type (11)]
-    expected: FAIL
-
   [CharacterData interface: calling replaceWith([object Object\],[object Object\]) on xmlDoc.createProcessingInstruction("abc", "def") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [CharacterData interface: document.createComment("abc") must inherit property "replaceWith" with the proper type (11)]
-    expected: FAIL
-
   [CharacterData interface: calling replaceWith([object Object\],[object Object\]) on document.createComment("abc") with too few arguments must throw TypeError]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/html/dom/interfaces.html.ini b/tests/wpt/metadata/html/dom/interfaces.html.ini
index 2e2eeeca4cf..a254db3f69b 100644
--- a/tests/wpt/metadata/html/dom/interfaces.html.ini
+++ b/tests/wpt/metadata/html/dom/interfaces.html.ini
@@ -1185,15 +1185,9 @@
   [Document interface: document.implementation.createDocument(null, "", null) must inherit property "all" with the proper type (81)]
     expected: FAIL
 
-  [Document interface: document.implementation.createDocument(null, "", null) must inherit property "prepend" with the proper type (87)]
-    expected: FAIL
-
   [Document interface: calling prepend([object Object\],[object Object\]) on document.implementation.createDocument(null, "", null) with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Document interface: document.implementation.createDocument(null, "", null) must inherit property "append" with the proper type (88)]
-    expected: FAIL
-
   [Document interface: calling append([object Object\],[object Object\]) on document.implementation.createDocument(null, "", null) with too few arguments must throw TypeError]
     expected: FAIL
 
@@ -2190,15 +2184,9 @@
   [Element interface: calling removeAttributeNode(Attr) on document.createElement("noscript") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Element interface: document.createElement("noscript") must inherit property "prepend" with the proper type (31)]
-    expected: FAIL
-
   [Element interface: calling prepend([object Object\],[object Object\]) on document.createElement("noscript") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Element interface: document.createElement("noscript") must inherit property "append" with the proper type (32)]
-    expected: FAIL
-
   [Element interface: calling append([object Object\],[object Object\]) on document.createElement("noscript") with too few arguments must throw TypeError]
     expected: FAIL
 
@@ -2214,15 +2202,9 @@
   [Element interface: calling queryAll(DOMString) on document.createElement("noscript") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Element interface: document.createElement("noscript") must inherit property "before" with the proper type (39)]
-    expected: FAIL
-
   [Element interface: calling before([object Object\],[object Object\]) on document.createElement("noscript") with too few arguments must throw TypeError]
     expected: FAIL
 
-  [Element interface: document.createElement("noscript") must inherit property "after" with the proper type (40)]
-    expected: FAIL
-
   [Element interface: calling after([object Object\],[object Object\]) on document.createElement("noscript") with too few arguments must throw TypeError]
     expected: FAIL
 
@@ -9519,9 +9501,6 @@
   [HTMLFontElement interface: document.createElement("font") must inherit property "size" with the proper type (2)]
     expected: FAIL
 
-  [Element interface: document.createElement("noscript") must inherit property "replaceWith" with the proper type (41)]
-    expected: FAIL
-
   [Element interface: calling replaceWith([object Object\],[object Object\]) on document.createElement("noscript") with too few arguments must throw TypeError]
     expected: FAIL