diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index c23eaa6f680..3491a8ed20e 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -1778,6 +1778,14 @@ impl TreeIterator {
                 self.current = Some(next_sibling);
                 return Some(current);
             }
+            if let Some(shadow_root) = ancestor.downcast::<ShadowRoot>() {
+                // Shadow roots don't have sibling, so after we're done traversing
+                // one we jump to the first child of the host
+                if let Some(child) = shadow_root.Host().upcast::<Node>().GetFirstChild() {
+                    self.current = Some(child);
+                    return Some(current);
+                }
+            }
             self.depth -= 1;
         }
         debug_assert_eq!(self.depth, 0);
@@ -1801,8 +1809,6 @@ impl Iterator for TreeIterator {
                     self.current = Some(DomRoot::from_ref(shadow_root.upcast::<Node>()));
                     self.depth += 1;
                     return Some(current);
-                } else {
-                    return self.next_skipping_children_impl(current);
                 }
             }
         }
diff --git a/tests/wpt/meta/custom-elements/CustomElementRegistry.html.ini b/tests/wpt/meta/custom-elements/CustomElementRegistry.html.ini
index 7b862b2d71c..bc33a16c596 100644
--- a/tests/wpt/meta/custom-elements/CustomElementRegistry.html.ini
+++ b/tests/wpt/meta/custom-elements/CustomElementRegistry.html.ini
@@ -1,6 +1,3 @@
 [CustomElementRegistry.html]
-  [customElements.define must upgrade elements in the shadow-including tree order]
-    expected: FAIL
-
   [customElements.define must get "observedAttributes" property on the constructor prototype when "attributeChangedCallback" is present]
     expected: FAIL
diff --git a/tests/wpt/meta/html/rendering/non-replaced-elements/the-fieldset-and-legend-elements/legend-in-slot.html.ini b/tests/wpt/meta/html/rendering/non-replaced-elements/the-fieldset-and-legend-elements/legend-in-slot.html.ini
deleted file mode 100644
index 4ed1ce5159e..00000000000
--- a/tests/wpt/meta/html/rendering/non-replaced-elements/the-fieldset-and-legend-elements/legend-in-slot.html.ini
+++ /dev/null
@@ -1,2 +0,0 @@
-[legend-in-slot.html]
-  expected: FAIL
diff --git a/tests/wpt/meta/html/semantics/embedded-content/the-canvas-element/canvas-descendants-focusability-004.tentative.html.ini b/tests/wpt/meta/html/semantics/embedded-content/the-canvas-element/canvas-descendants-focusability-004.tentative.html.ini
index 5316effdce5..1900b9aedd1 100644
--- a/tests/wpt/meta/html/semantics/embedded-content/the-canvas-element/canvas-descendants-focusability-004.tentative.html.ini
+++ b/tests/wpt/meta/html/semantics/embedded-content/the-canvas-element/canvas-descendants-focusability-004.tentative.html.ini
@@ -1,2 +1,15 @@
 [canvas-descendants-focusability-004.tentative.html]
-  expected: TIMEOUT
+  [<button data-focusable="false">]
+    expected: FAIL
+
+  [<section tabindex="-1" data-focusable="false">]
+    expected: FAIL
+
+  [<div tabindex="-1" data-focusable="false">]
+    expected: FAIL
+
+  [<span tabindex="-1" data-focusable="false">]
+    expected: FAIL
+
+  [<a href="#" data-focusable="false">]
+    expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/DocumentOrShadowRoot-prototype-elementFromPoint.html.ini b/tests/wpt/meta/shadow-dom/DocumentOrShadowRoot-prototype-elementFromPoint.html.ini
index 3cc32e416f7..2591bcdd066 100644
--- a/tests/wpt/meta/shadow-dom/DocumentOrShadowRoot-prototype-elementFromPoint.html.ini
+++ b/tests/wpt/meta/shadow-dom/DocumentOrShadowRoot-prototype-elementFromPoint.html.ini
@@ -100,3 +100,6 @@
 
   [elementsFromPoint should return all elements under a point, even when context object is not connected]
     expected: FAIL
+
+  [document.elementFromPoint and shadowRoot.elementFromPoint must return the element assigned to a slot when hit-tested text node under an element is assigned to a slot in the shadow tree and the shadow host of the slot has display: inline]
+    expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/declarative/declarative-after-attachshadow.html.ini b/tests/wpt/meta/shadow-dom/declarative/declarative-after-attachshadow.html.ini
deleted file mode 100644
index 80e5b44150b..00000000000
--- a/tests/wpt/meta/shadow-dom/declarative/declarative-after-attachshadow.html.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[declarative-after-attachshadow.html]
-  [Declarative Shadow DOM: declarative shadow should fail if attachShadow() already called]
-    expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/declarative/innerhtml-on-ordinary-template.html.ini b/tests/wpt/meta/shadow-dom/declarative/innerhtml-on-ordinary-template.html.ini
deleted file mode 100644
index 55cf7e0ec37..00000000000
--- a/tests/wpt/meta/shadow-dom/declarative/innerhtml-on-ordinary-template.html.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[innerhtml-on-ordinary-template.html]
-  [Declarative Shadow DOM: innerHTML should work on <template shadowroot> that is left over]
-    expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/event-inside-slotted-node.html.ini b/tests/wpt/meta/shadow-dom/event-inside-slotted-node.html.ini
deleted file mode 100644
index 5186d4b5b5f..00000000000
--- a/tests/wpt/meta/shadow-dom/event-inside-slotted-node.html.ini
+++ /dev/null
@@ -1,60 +0,0 @@
-[event-inside-slotted-node.html]
-  [Firing an event inside a grand child of a detached open mode shadow host]
-    expected: FAIL
-
-  [Firing an event inside a grand child of a detached closed mode shadow host]
-    expected: FAIL
-
-  [Firing an event inside a grand child of an in-document open mode shadow host]
-    expected: FAIL
-
-  [Firing an event inside a grand child of an in-document closed mode shadow host]
-    expected: FAIL
-
-  [Firing an event on a node with two ancestors with a detached open and open shadow trees with an inner open shadow tree]
-    expected: FAIL
-
-  [Firing an event on a node with two ancestors with a detached open and open shadow trees with an inner closed shadow tree]
-    expected: FAIL
-
-  [Firing an event on a node with two ancestors with a detached open and closed shadow trees with an inner open shadow tree]
-    expected: FAIL
-
-  [Firing an event on a node with two ancestors with a detached open and closed shadow trees with an inner closed shadow tree]
-    expected: FAIL
-
-  [Firing an event on a node with two ancestors with a detached closed and open shadow trees with an inner open shadow tree]
-    expected: FAIL
-
-  [Firing an event on a node with two ancestors with a detached closed and open shadow trees with an inner closed shadow tree]
-    expected: FAIL
-
-  [Firing an event on a node with two ancestors with a detached closed and closed shadow trees with an inner open shadow tree]
-    expected: FAIL
-
-  [Firing an event on a node with two ancestors with a detached closed and closed shadow trees with an inner closed shadow tree]
-    expected: FAIL
-
-  [Firing an event on a node within a open shadow tree that is itself a open shadow tree (the latter being the descendent of a host for a separate open shadow tree)]
-    expected: FAIL
-
-  [Firing an event on a node within a closed shadow tree that is itself a open shadow tree (the latter being the descendent of a host for a separate open shadow tree)]
-    expected: FAIL
-
-  [Firing an event on a node within a open shadow tree that is itself a closed shadow tree (the latter being the descendent of a host for a separate open shadow tree)]
-    expected: FAIL
-
-  [Firing an event on a node within a closed shadow tree that is itself a closed shadow tree (the latter being the descendent of a host for a separate open shadow tree)]
-    expected: FAIL
-
-  [Firing an event on a node within a open shadow tree that is itself a open shadow tree (the latter being the descendent of a host for a separate closed shadow tree)]
-    expected: FAIL
-
-  [Firing an event on a node within a closed shadow tree that is itself a open shadow tree (the latter being the descendent of a host for a separate closed shadow tree)]
-    expected: FAIL
-
-  [Firing an event on a node within a open shadow tree that is itself a closed shadow tree (the latter being the descendent of a host for a separate closed shadow tree)]
-    expected: FAIL
-
-  [Firing an event on a node within a closed shadow tree that is itself a closed shadow tree (the latter being the descendent of a host for a separate closed shadow tree)]
-    expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/offsetParent-across-shadow-boundaries.html.ini b/tests/wpt/meta/shadow-dom/offsetParent-across-shadow-boundaries.html.ini
index 5df3c73d89c..afd8ee2cf06 100644
--- a/tests/wpt/meta/shadow-dom/offsetParent-across-shadow-boundaries.html.ini
+++ b/tests/wpt/meta/shadow-dom/offsetParent-across-shadow-boundaries.html.ini
@@ -22,15 +22,3 @@
 
   [offsetParent must find the first offset parent which is a shadow-including ancestor of the context object even some shadow tree of closed mode did not have any offset parent]
     expected: FAIL
-
-  [offsetParent must return null on a child element of a shadow host for the shadow tree in open mode which is not assigned to any slot]
-    expected: FAIL
-
-  [offsetParent must return null on a child element of a shadow host for the shadow tree in closed mode which is not assigned to any slot]
-    expected: FAIL
-
-  [offsetParent must return null on a child element of a shadow host for the shadow tree in open mode which is not in the flat tree]
-    expected: FAIL
-
-  [offsetParent must return null on a child element of a shadow host for the shadow tree in closed mode which is not in the flat tree]
-    expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/slot-fallback-content-008.html.ini b/tests/wpt/meta/shadow-dom/slot-fallback-content-008.html.ini
deleted file mode 100644
index aaa3b56bdce..00000000000
--- a/tests/wpt/meta/shadow-dom/slot-fallback-content-008.html.ini
+++ /dev/null
@@ -1,2 +0,0 @@
-[slot-fallback-content-008.html]
-  expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/slotchange.html.ini b/tests/wpt/meta/shadow-dom/slotchange.html.ini
deleted file mode 100644
index 9d7b8d03151..00000000000
--- a/tests/wpt/meta/shadow-dom/slotchange.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[slotchange.html]
-  expected: TIMEOUT
-  [slotchange event: Child content is added to nested slots.]
-    expected: TIMEOUT
diff --git a/tests/wpt/meta/shadow-dom/slots-fallback.html.ini b/tests/wpt/meta/shadow-dom/slots-fallback.html.ini
index ded66b0676b..56471543af4 100644
--- a/tests/wpt/meta/shadow-dom/slots-fallback.html.ini
+++ b/tests/wpt/meta/shadow-dom/slots-fallback.html.ini
@@ -1,18 +1,3 @@
 [slots-fallback.html]
-  [Slots fallback: Complex case.]
-    expected: FAIL
-
-  [Slots fallback: Complex case, elements only.]
-    expected: FAIL
-
-  [Slots fallback: Mutation. Append fallback contents.]
-    expected: FAIL
-
-  [Slots fallback: Mutation. Remove fallback contents.]
-    expected: FAIL
-
-  [Slots fallback: Mutation. Assign a node to a slot so that fallback contens are no longer used.]
-    expected: FAIL
-
   [Slots fallback: Mutation.  Remove a slot which is a fallback content of another slot.]
     expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/slots.html.ini b/tests/wpt/meta/shadow-dom/slots.html.ini
index e460db55d88..daac1c24549 100644
--- a/tests/wpt/meta/shadow-dom/slots.html.ini
+++ b/tests/wpt/meta/shadow-dom/slots.html.ini
@@ -1,36 +1,3 @@
 [slots.html]
-  [Slots: Slot is assigned to another slot]
-    expected: FAIL
-
-  [Slots: Open > Closed.]
-    expected: FAIL
-
-  [Slots: Closed > Closed.]
-    expected: FAIL
-
-  [Slots: Closed > Open.]
-    expected: FAIL
-
-  [Slots: Complex case: Basi line.]
-    expected: FAIL
-
-  [Slots: Mutation: appendChild.]
-    expected: FAIL
-
-  [Slots: Mutation: Change slot= attribute 2.]
-    expected: FAIL
-
-  [Slots: Mutation: Change slot= attribute 3.]
-    expected: FAIL
-
-  [Slots: Mutation: Add a slot: before.]
-    expected: FAIL
-
-  [Slots: Mutation: Change slot name= attribute.]
-    expected: FAIL
-
-  [Slots: Mutation: Change slot slot= attribute.]
-    expected: FAIL
-
   [Slots: Mutation: Remove a slot.]
     expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/dom-tree-accessors-001.html.ini b/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/dom-tree-accessors-001.html.ini
index 866e5e11ac3..268e7a2902a 100644
--- a/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/dom-tree-accessors-001.html.ini
+++ b/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/dom-tree-accessors-001.html.ini
@@ -1,6 +1,3 @@
 [dom-tree-accessors-001.html]
-  [Elements in a shadow tree should not be accessible from owner document's getElementsByName() method.]
-    expected: FAIL
-
   [Elements in a shadow tree should not be accessible from owner document's "all" attribute.]
     expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/selectors-api-001.html.ini b/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/selectors-api-001.html.ini
deleted file mode 100644
index b8dd91e20ff..00000000000
--- a/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/selectors-api-001.html.ini
+++ /dev/null
@@ -1,6 +0,0 @@
-[selectors-api-001.html]
-  [Elements in a shadow tree should not be accessible from owner document's querySelector() method.]
-    expected: FAIL
-
-  [Elements in a shadow tree should not be accessible from owner document's querySelectorAll() method.]
-    expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/test-009.html.ini b/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/test-009.html.ini
deleted file mode 100644
index a7be7076026..00000000000
--- a/tests/wpt/meta/shadow-dom/untriaged/shadow-trees/upper-boundary-encapsulation/test-009.html.ini
+++ /dev/null
@@ -1,33 +0,0 @@
-[test-009.html]
-  [A_04_01_09_T01]
-    expected: FAIL
-
-  [A_04_01_09_T03]
-    expected: FAIL
-
-  [A_04_01_09_T05]
-    expected: FAIL
-
-  [A_04_01_09_T08]
-    expected: FAIL
-
-  [A_04_01_09_T09]
-    expected: FAIL
-
-  [A_04_01_09_T10]
-    expected: FAIL
-
-  [A_04_01_09_T11]
-    expected: FAIL
-
-  [A_04_01_09_T12]
-    expected: FAIL
-
-  [A_04_01_09_T14]
-    expected: FAIL
-
-  [A_04_01_09_T15]
-    expected: FAIL
-
-  [A_04_01_09_T16]
-    expected: FAIL
diff --git a/tests/wpt/meta/shadow-dom/untriaged/styles/test-008.html.ini b/tests/wpt/meta/shadow-dom/untriaged/styles/test-008.html.ini
deleted file mode 100644
index d758520ec6c..00000000000
--- a/tests/wpt/meta/shadow-dom/untriaged/styles/test-008.html.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[test-008.html]
-  [A_06_00_09_T01]
-    expected: FAIL