diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index d6692fc13cb..a7d068a86a4 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -2086,11 +2086,14 @@ class CGDefineProxyHandler(CGAbstractMethod):
         return CGAbstractMethod.define(self)
 
     def definition_body(self):
+        customDefineProperty = 'defineProperty_'
+        if self.descriptor.operations['IndexedSetter'] or self.descriptor.operations['NamedSetter']:
+            customDefineProperty = 'defineProperty'
         body = """\
 let traps = ProxyTraps {
   getPropertyDescriptor: Some(getPropertyDescriptor),
   getOwnPropertyDescriptor: Some(getOwnPropertyDescriptor),
-  defineProperty: Some(defineProperty_),
+  defineProperty: Some(%s),
   getOwnPropertyNames: ptr::null(),
   delete_: Some(delete_),
   enumerate: ptr::null(),
@@ -2120,7 +2123,7 @@ let traps = ProxyTraps {
 };
 
 CreateProxyHandler(&traps, &Class as *const _ as *const _)
-""" % (FINALIZE_HOOK_NAME,
+""" % (customDefineProperty, FINALIZE_HOOK_NAME,
        TRACE_HOOK_NAME)
         return CGGeneric(body)
 
@@ -2276,8 +2279,15 @@ class CGPerSignatureCall(CGThing):
                                              invalidEnumValueFatal=not setter) for
                          i in range(argConversionStartsAt, self.argCount)])
 
+        errorResult = None
+        if self.isFallible():
+            if nativeMethodName == "NamedSetter":
+                errorResult = " false"
+            else:
+                errorResult = " false as JSBool"
+
         cgThings.append(CGCallGenerator(
-                    ' false as JSBool' if self.isFallible() else None,
+                    errorResult,
                     self.getArguments(), self.argsPre, returnType,
                     self.extendedAttributes, descriptor, nativeMethodName,
                     static))
@@ -3836,14 +3846,14 @@ if expando.is_not_null() {
             getIndexedOrExpando = getFromExpando + "\n"
 
         namedGetter = self.descriptor.operations['NamedGetter']
-        if namedGetter and False: #XXXjdm unfinished
-            getNamed = ("if (JSID_IS_STRING(id)) {\n" +
+        if namedGetter:
+            getNamed = ("if (RUST_JSID_IS_STRING(id) != 0) {\n" +
                         "  let name = jsid_to_str(cx, id);\n" +
                         "  let this = UnwrapProxy(proxy);\n" +
                         "  let this = JS::from_raw(this);\n" +
                         "  let this = this.root();\n" +
                         CGIndenter(CGProxyNamedGetter(self.descriptor, templateValues)).define() +
-                        "}\n") % (self.descriptor.concreteType)
+                        "}\n")
         else:
             getNamed = ""
 
diff --git a/components/script/dom/domstringmap.rs b/components/script/dom/domstringmap.rs
index 26218445c80..ff4990eb5f6 100644
--- a/components/script/dom/domstringmap.rs
+++ b/components/script/dom/domstringmap.rs
@@ -2,51 +2,56 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::DOMStringMapBinding;
 use dom::bindings::codegen::Bindings::DOMStringMapBinding::DOMStringMapMethods;
+use dom::bindings::error::ErrorResult;
 use dom::bindings::global::GlobalRef;
-use dom::bindings::js::{JSRef, Temporary};
+use dom::bindings::js::{JS, JSRef, Temporary};
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
+use dom::node::window_from_node;
+use dom::htmlelement::{HTMLElement, HTMLElementCustomAttributeHelpers};
 use servo_util::str::DOMString;
 
-use std::collections::HashMap;
-
 #[dom_struct]
 pub struct DOMStringMap {
-    map: DOMRefCell<HashMap<DOMString, DOMString>>,
     reflector_: Reflector,
+    element: JS<HTMLElement>,
 }
 
 impl DOMStringMap {
-    fn new_inherited() -> DOMStringMap {
+    fn new_inherited(element: JSRef<HTMLElement>) -> DOMStringMap {
         DOMStringMap {
-            map: DOMRefCell::new(HashMap::new()),
             reflector_: Reflector::new(),
+            element: JS::from_rooted(element),
         }
     }
 
-    pub fn new(global: GlobalRef) -> Temporary<DOMStringMap> {
-        reflect_dom_object(box DOMStringMap::new_inherited(),
-                           global, DOMStringMapBinding::Wrap)
+    pub fn new(element: JSRef<HTMLElement>) -> Temporary<DOMStringMap> {
+        let window = window_from_node(element).root();
+        reflect_dom_object(box DOMStringMap::new_inherited(element),
+                           GlobalRef::Window(window.root_ref()), DOMStringMapBinding::Wrap)
     }
 }
 
+// https://html.spec.whatwg.org/#domstringmap
 impl<'a> DOMStringMapMethods for JSRef<'a, DOMStringMap> {
-    fn NamedCreator(self, name: DOMString, value: DOMString) {
-        self.map.borrow_mut().insert(name, value);
+    fn NamedCreator(self, name: DOMString, value: DOMString) -> ErrorResult {
+        self.NamedSetter(name, value)
     }
 
     fn NamedDeleter(self, name: DOMString) {
-        self.map.borrow_mut().remove(&name);
+        let element = self.element.root();
+        element.delete_custom_attr(name)
     }
 
-    fn NamedSetter(self, name: DOMString, value: DOMString) {
-        self.map.borrow_mut().insert(name, value);
+    fn NamedSetter(self, name: DOMString, value: DOMString) -> ErrorResult {
+        let element = self.element.root();
+        element.set_custom_attr(name, value)
     }
 
     fn NamedGetter(self, name: DOMString, found: &mut bool) -> DOMString {
-        match self.map.borrow().get(&name) {
+        let element = self.element.root();
+        match element.get_custom_attr(name) {
             Some(value) => {
                 *found = true;
                 value.clone()
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 00f481dcd32..1c069ea3aa3 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -459,6 +459,7 @@ impl LayoutElementHelpers for JS<Element> {
 pub trait ElementHelpers<'a> {
     fn html_element_in_html_document(self) -> bool;
     fn local_name(self) -> &'a Atom;
+    fn parsed_name(self, name: DOMString) -> DOMString;
     fn namespace(self) -> &'a Namespace;
     fn prefix(self) -> &'a Option<DOMString>;
     fn attrs(&self) -> Ref<Vec<JS<Attr>>>;
@@ -481,6 +482,15 @@ impl<'a> ElementHelpers<'a> for JSRef<'a, Element> {
         &self.extended_deref().local_name
     }
 
+    // https://dom.spec.whatwg.org/#concept-element-attributes-get-by-name
+    fn parsed_name(self, name: DOMString) -> DOMString {
+        if self.html_element_in_html_document() {
+            name.as_slice().to_ascii_lower()
+        } else {
+            name
+        }
+    }
+
     fn namespace(self) -> &'a Namespace {
         &self.extended_deref().namespace
     }
@@ -609,6 +619,7 @@ pub trait AttributeHandlers {
                                  value: DOMString,
                                  prefix: Option<DOMString>);
     fn set_attribute(self, name: &Atom, value: AttrValue);
+    fn set_custom_attribute(self, name: DOMString, value: DOMString) -> ErrorResult;
     fn do_set_attribute(self, local_name: Atom, value: AttrValue,
                         name: Atom, namespace: Namespace,
                         prefix: Option<DOMString>, cb: |JSRef<Attr>| -> bool);
@@ -678,6 +689,23 @@ impl<'a> AttributeHandlers for JSRef<'a, Element> {
             ns!(""), None, |attr| *attr.local_name() == *name);
     }
 
+    // https://html.spec.whatwg.org/multipage/dom.html#attr-data-*
+    fn set_custom_attribute(self, name: DOMString, value: DOMString) -> ErrorResult {
+        // Step 1.
+        match xml_name_type(name.as_slice()) {
+            InvalidXMLName => return Err(InvalidCharacter),
+            _ => {}
+        }
+
+        // Steps 2-5.
+        let name = Atom::from_slice(name.as_slice());
+        let value = self.parse_attribute(&ns!(""), &name, value);
+        self.do_set_attribute(name.clone(), value, name.clone(), ns!(""), None, |attr| {
+            *attr.name() == name && *attr.namespace() == ns!("")
+        });
+        Ok(())
+    }
+
     fn do_set_attribute(self, local_name: Atom, value: AttrValue,
                         name: Atom, namespace: Namespace,
                         prefix: Option<DOMString>, cb: |JSRef<Attr>| -> bool) {
@@ -902,11 +930,7 @@ impl<'a> ElementMethods for JSRef<'a, Element> {
 
     // http://dom.spec.whatwg.org/#dom-element-getattribute
     fn GetAttribute(self, name: DOMString) -> Option<DOMString> {
-        let name = if self.html_element_in_html_document() {
-            name.as_slice().to_ascii_lower()
-        } else {
-            name
-        };
+        let name = self.parsed_name(name);
         self.get_attribute(ns!(""), &Atom::from_slice(name.as_slice())).root()
                      .map(|s| s.Value())
     }
@@ -931,17 +955,13 @@ impl<'a> ElementMethods for JSRef<'a, Element> {
         }
 
         // Step 2.
-        let name = if self.html_element_in_html_document() {
-            name.as_slice().to_ascii_lower()
-        } else {
-            name
-        };
+        let name = self.parsed_name(name);
 
         // Step 3-5.
         let name = Atom::from_slice(name.as_slice());
         let value = self.parse_attribute(&ns!(""), &name, value);
         self.do_set_attribute(name.clone(), value, name.clone(), ns!(""), None, |attr| {
-            attr.name().as_slice() == name.as_slice()
+            *attr.name() == name
         });
         Ok(())
     }
@@ -1012,11 +1032,7 @@ impl<'a> ElementMethods for JSRef<'a, Element> {
 
     // http://dom.spec.whatwg.org/#dom-element-removeattribute
     fn RemoveAttribute(self, name: DOMString) {
-        let name = if self.html_element_in_html_document() {
-            name.as_slice().to_ascii_lower()
-        } else {
-            name
-        };
+        let name = self.parsed_name(name);
         self.remove_attribute(ns!(""), name.as_slice())
     }
 
diff --git a/components/script/dom/htmlelement.rs b/components/script/dom/htmlelement.rs
index e38ab5ff523..f36e84a078e 100644
--- a/components/script/dom/htmlelement.rs
+++ b/components/script/dom/htmlelement.rs
@@ -13,10 +13,13 @@ use dom::bindings::codegen::InheritTypes::{ElementCast, HTMLFrameSetElementDeriv
 use dom::bindings::codegen::InheritTypes::{EventTargetCast, HTMLInputElementCast};
 use dom::bindings::codegen::InheritTypes::{HTMLElementDerived, HTMLBodyElementDerived};
 use dom::bindings::js::{JSRef, Temporary, MutNullableJS};
+use dom::bindings::error::ErrorResult;
+use dom::bindings::error::Error::Syntax;
 use dom::bindings::utils::{Reflectable, Reflector};
 use dom::cssstyledeclaration::CSSStyleDeclaration;
 use dom::document::Document;
-use dom::element::{Element, ElementTypeId, ActivationElementHelpers};
+use dom::domstringmap::DOMStringMap;
+use dom::element::{Element, ElementTypeId, ActivationElementHelpers, AttributeHandlers};
 use dom::eventtarget::{EventTarget, EventTargetHelpers, EventTargetTypeId};
 use dom::node::{Node, NodeTypeId, window_from_node};
 use dom::virtualmethods::VirtualMethods;
@@ -31,6 +34,7 @@ use std::default::Default;
 pub struct HTMLElement {
     element: Element,
     style_decl: MutNullableJS<CSSStyleDeclaration>,
+    dataset: MutNullableJS<DOMStringMap>,
 }
 
 impl HTMLElementDerived for EventTarget {
@@ -48,6 +52,7 @@ impl HTMLElement {
         HTMLElement {
             element: Element::new_inherited(type_id, tag_name, ns!(HTML), prefix, document),
             style_decl: Default::default(),
+            dataset: Default::default(),
         }
     }
 
@@ -89,6 +94,11 @@ impl<'a> HTMLElementMethods for JSRef<'a, HTMLElement> {
 
     global_event_handlers!(NoOnload)
 
+    // https://html.spec.whatwg.org/multipage/dom.html#dom-dataset
+    fn Dataset(self) -> Temporary<DOMStringMap> {
+        self.dataset.or_init(|| DOMStringMap::new(self))
+    }
+
     fn GetOnload(self) -> Option<EventHandlerNonNull> {
         if self.is_body_or_frameset() {
             let win = window_from_node(self).root();
@@ -122,6 +132,51 @@ impl<'a> HTMLElementMethods for JSRef<'a, HTMLElement> {
     }
 }
 
+// https://html.spec.whatwg.org/#attr-data-*
+pub trait HTMLElementCustomAttributeHelpers {
+    fn set_custom_attr(self, name: DOMString, value: DOMString) -> ErrorResult;
+    fn get_custom_attr(self, name: DOMString) -> Option<DOMString>;
+    fn delete_custom_attr(self, name: DOMString);
+}
+
+fn to_snake_case(name: DOMString) -> DOMString {
+    let mut attr_name = "data-".into_string();
+    for ch in name.as_slice().chars() {
+        if ch.is_uppercase() {
+            attr_name.push('\x2d');
+            attr_name.push(ch.to_lowercase());
+        } else {
+            attr_name.push(ch);
+        }
+    }
+    attr_name
+}
+
+impl<'a> HTMLElementCustomAttributeHelpers for JSRef<'a, HTMLElement> {
+    fn set_custom_attr(self, name: DOMString, value: DOMString) -> ErrorResult {
+        if name.as_slice().chars()
+               .skip_while(|&ch| ch != '\u002d')
+               .nth(1).map_or(false, |ch| ch as u8 - b'a' < 26) {
+            return Err(Syntax);
+        }
+        let element: JSRef<Element> = ElementCast::from_ref(self);
+        element.set_custom_attribute(to_snake_case(name), value)
+    }
+
+    fn get_custom_attr(self, name: DOMString) -> Option<DOMString> {
+        let element: JSRef<Element> = ElementCast::from_ref(self);
+        element.get_attribute(ns!(""), &Atom::from_slice(to_snake_case(name).as_slice())).map(|attr| {
+            let attr = attr.root();
+            attr.value().as_slice().to_string()
+        })
+    }
+
+    fn delete_custom_attr(self, name: DOMString) {
+        let element: JSRef<Element> = ElementCast::from_ref(self);
+        element.remove_attribute(ns!(""), to_snake_case(name).as_slice())
+    }
+}
+
 impl<'a> VirtualMethods for JSRef<'a, HTMLElement> {
     fn super_type<'a>(&'a self) -> Option<&'a VirtualMethods> {
         let element: &JSRef<Element> = ElementCast::from_borrowed_ref(self);
diff --git a/components/script/dom/webidls/DOMStringMap.webidl b/components/script/dom/webidls/DOMStringMap.webidl
index aa4d3ed9673..c11d47c5a85 100644
--- a/components/script/dom/webidls/DOMStringMap.webidl
+++ b/components/script/dom/webidls/DOMStringMap.webidl
@@ -7,6 +7,7 @@
 [OverrideBuiltins]
 interface DOMStringMap {
   getter DOMString (DOMString name);
+  [Throws]
   setter creator void (DOMString name, DOMString value);
   deleter void (DOMString name);
 };
diff --git a/components/script/dom/webidls/HTMLElement.webidl b/components/script/dom/webidls/HTMLElement.webidl
index 39c7699900d..90ef09d7a9f 100644
--- a/components/script/dom/webidls/HTMLElement.webidl
+++ b/components/script/dom/webidls/HTMLElement.webidl
@@ -10,7 +10,7 @@ interface HTMLElement : Element {
            attribute DOMString lang;
   //         attribute boolean translate;
   //         attribute DOMString dir;
-  //readonly attribute DOMStringMap dataset;
+  readonly attribute DOMStringMap dataset;
 
   // microdata
   //         attribute boolean itemScope;
diff --git a/components/script/tests.rs b/components/script/tests.rs
index 8f7bbda8385..e4636c5b5ad 100644
--- a/components/script/tests.rs
+++ b/components/script/tests.rs
@@ -41,8 +41,8 @@ macro_rules! sizeof_checker (
 sizeof_checker!(size_event_target, EventTarget, 56)
 sizeof_checker!(size_node, Node, 304)
 sizeof_checker!(size_element, Element, 448)
-sizeof_checker!(size_htmlelement, HTMLElement, 464)
-sizeof_checker!(size_div, HTMLDivElement, 464)
-sizeof_checker!(size_span, HTMLSpanElement, 464)
+sizeof_checker!(size_htmlelement, HTMLElement, 480)
+sizeof_checker!(size_div, HTMLDivElement, 480)
+sizeof_checker!(size_span, HTMLSpanElement, 480)
 sizeof_checker!(size_text, Text, 336)
 sizeof_checker!(size_characterdata, CharacterData, 336)
diff --git a/tests/wpt/metadata/html/dom/elements/global-attributes/custom-attrs.html.ini b/tests/wpt/metadata/html/dom/elements/global-attributes/custom-attrs.html.ini
deleted file mode 100644
index 2a68450037d..00000000000
--- a/tests/wpt/metadata/html/dom/elements/global-attributes/custom-attrs.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[custom-attrs.html]
-  type: testharness
-  [Setting an Element\'s dataset property should not interfere with namespaced attributes with same name]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/html/dom/elements/global-attributes/data_unicode_attr.html.ini b/tests/wpt/metadata/html/dom/elements/global-attributes/data_unicode_attr.html.ini
deleted file mode 100644
index 7590d513387..00000000000
--- a/tests/wpt/metadata/html/dom/elements/global-attributes/data_unicode_attr.html.ini
+++ /dev/null
@@ -1,8 +0,0 @@
-[data_unicode_attr.html]
-  type: testharness
-  [dataset - SBCS]
-    expected: FAIL
-
-  [dataset - UNICODE]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-delete.html.ini b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-delete.html.ini
index a88947eac79..5718c7b3ebb 100644
--- a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-delete.html.ini
+++ b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-delete.html.ini
@@ -12,9 +12,6 @@
   [Deleting element.dataset[\'Foo\'\] should also remove an attribute with name \'data--foo\' should it exist.]
     expected: FAIL
 
-  [Deleting element.dataset[\'-foo\'\] should also remove an attribute with name \'data--foo\' should it exist.]
-    expected: FAIL
-
   [Deleting element.dataset[\'-Foo\'\] should also remove an attribute with name \'data---foo\' should it exist.]
     expected: FAIL
 
@@ -24,6 +21,3 @@
   [Deleting element.dataset[\'\xc3\xa0\'\] should also remove an attribute with name \'data-\xc3\xa0\' should it exist.]
     expected: FAIL
 
-  [Deleting element.dataset[\'foo\'\] should not throw if even if the element does now have an attribute with the name data-foo.]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-enumeration.html.ini b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-enumeration.html.ini
index 7b228c9e6ea..4dd8405e31c 100644
--- a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-enumeration.html.ini
+++ b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-enumeration.html.ini
@@ -1,8 +1,3 @@
 [dataset-enumeration.html]
   type: testharness
-  [A dataset should be enumeratable.]
-    expected: FAIL
-
-  [Only attributes who qualify as dataset properties should be enumeratable in the dataset.]
-    expected: FAIL
-
+  expected: CRASH
diff --git a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-get.html.ini b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-get.html.ini
index 135cbd44b1a..f6649ae7398 100644
--- a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-get.html.ini
+++ b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-get.html.ini
@@ -1,32 +1,3 @@
 [dataset-get.html]
   type: testharness
-  [Getting element.dataset[\'foo\'\] should return the value of element.getAttribute(\'data-foo\')\']
-    expected: FAIL
-
-  [Getting element.dataset[\'fooBar\'\] should return the value of element.getAttribute(\'data-foo-bar\')\']
-    expected: FAIL
-
-  [Getting element.dataset[\'-\'\] should return the value of element.getAttribute(\'data--\')\']
-    expected: FAIL
-
-  [Getting element.dataset[\'Foo\'\] should return the value of element.getAttribute(\'data--foo\')\']
-    expected: FAIL
-
-  [Getting element.dataset[\'-Foo\'\] should return the value of element.getAttribute(\'data---foo\')\']
-    expected: FAIL
-
-  [Getting element.dataset[\'foo\'\] should return the value of element.getAttribute(\'data-Foo\')\']
-    expected: FAIL
-
-  [Getting element.dataset[\'\'\] should return the value of element.getAttribute(\'data-\')\']
-    expected: FAIL
-
-  [Getting element.dataset[\'\xc3\xa0\'\] should return the value of element.getAttribute(\'data-\xc3\xa0\')\']
-    expected: FAIL
-
-  [Getting element.dataset[\'toString\'\] should return the value of element.getAttribute(\'data-to-string\')\']
-    expected: FAIL
-
-  [Tests that an attribute named dataFoo does not make an entry in the dataset DOMStringMap.]
-    expected: FAIL
-
+  expected: CRASH
diff --git a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-prototype.html.ini b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-prototype.html.ini
deleted file mode 100644
index 69c8e9c2f83..00000000000
--- a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-prototype.html.ini
+++ /dev/null
@@ -1,8 +0,0 @@
-[dataset-prototype.html]
-  type: testharness
-  [An elements dataset property is an instance of a DOMStringMap]
-    expected: FAIL
-
-  [Properties on Object.prototype should shine through.]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-set.html.ini b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-set.html.ini
index de7d444eca4..8887ec05b9e 100644
--- a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-set.html.ini
+++ b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset-set.html.ini
@@ -1,32 +1,5 @@
 [dataset-set.html]
   type: testharness
-  [Setting element.dataset[\'foo\'\] should also change the value of element.getAttribute(\'data-foo\')\']
-    expected: FAIL
-
-  [Setting element.dataset[\'fooBar\'\] should also change the value of element.getAttribute(\'data-foo-bar\')\']
-    expected: FAIL
-
-  [Setting element.dataset[\'-\'\] should also change the value of element.getAttribute(\'data--\')\']
-    expected: FAIL
-
-  [Setting element.dataset[\'Foo\'\] should also change the value of element.getAttribute(\'data--foo\')\']
-    expected: FAIL
-
-  [Setting element.dataset[\'-Foo\'\] should also change the value of element.getAttribute(\'data---foo\')\']
-    expected: FAIL
-
-  [Setting element.dataset[\'\'\] should also change the value of element.getAttribute(\'data-\')\']
-    expected: FAIL
-
-  [Setting element.dataset[\'\xc3\xa0\'\] should also change the value of element.getAttribute(\'data-\xc3\xa0\')\']
-    expected: FAIL
-
-  [Setting element.dataset[\'-foo\'\] should throw a SYNTAX_ERR\']
-    expected: FAIL
-
-  [Setting element.dataset[\'foo \'\] should throw an INVALID_CHARACTER_ERR\']
-    expected: FAIL
-
   [Setting element.dataset[\'foo\xef\xa4\x80\'\] should throw an INVALID_CHARACTER_ERR\']
     expected: FAIL
 
diff --git a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset.html.ini b/tests/wpt/metadata/html/dom/elements/global-attributes/dataset.html.ini
deleted file mode 100644
index 299c83c3c93..00000000000
--- a/tests/wpt/metadata/html/dom/elements/global-attributes/dataset.html.ini
+++ /dev/null
@@ -1,14 +0,0 @@
-[dataset.html]
-  type: testharness
-  [Should return \'undefined\' before setting an attribute]
-    expected: FAIL
-
-  [Should return \'value\' if that\'s the value]
-    expected: FAIL
-
-  [Should return the empty string if that\'s the value]
-    expected: FAIL
-
-  [Should return \'undefined\' after removing an attribute]
-    expected: FAIL
-